sys: Don't pass RF_ALLOCATED to bus_alloc_resource*

This is a nop as eventually these flags are passed to rman_reserve_resource
which unconditionally sets RF_ALLOCATED in the new flags for a region.
However, it's really a layering violation to use RF_ALLOCATED in relation
to struct resource objects outside of subr_rman.c as subr_rman.c uses
this flag to manage it's internal tracking of allocated vs free regions.

In addition, don't document this as a valid flag in the manual.  I
think the intention here was that if a caller didn't want to pass
RF_ACTIVE or RF_SHAREABLE, they could pass RF_ALLOCATED instead of 0,
but given the layering violation, I think it's best to just pass 0
instead in that case.

NB: The bhnd bus uses RF_ALLOCATED (along with RF_ACTIVE) in a
separate API to manage resource regions that are not struct resource
objects (but a separate wrapper object).  It would perhaps be cleaner
if the chipc_retain_region and chipc_release_region functions used
their own flag constants instead of reusing the rman(9) flags.

Reviewed by:	imp, kib
Differential Revision:	https://reviews.freebsd.org/D55683

share/man/man9/bus_alloc_resource.9

@@ -26,7 +26,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd October 30, 2025
+.Dd March 6, 2026
 .Dt BUS_ALLOC_RESOURCE 9
 .Os
 .Sh NAME
@@ -142,12 +142,8 @@ is used, if it is bigger than the default value.
 .It
 .Fa flags
 sets the flags for the resource.
-You can set one or more of these flags:
-.Bl -tag -width RF_SHAREABLE
-.It Dv RF_ALLOCATED
-resource has been reserved.
-The resource still needs to be activated with
-.Xr bus_activate_resource 9 .
+You can set zero or more of these flags:
+.Bl -tag -width RF_PREFETCHABLE
 .It Dv RF_ACTIVE
 activate resource atomically.
 .It Dv RF_PREFETCHABLE

sys/arm/nvidia/tegra_pcie.c

@@ -1468,7 +1468,7 @@ tegra_pcib_attach(device_t dev)
 	}
 	/*
 	 * XXX - FIXME
-	 * tag for config space is not filled when RF_ALLOCATED flag is used.
+	 * tag for config space is not filled when RF_ACTIVE flag is not used.
 	 */
 	sc->bus_tag = rman_get_bustag(sc->pads_mem_res);
 
@@ -1482,8 +1482,7 @@ tegra_pcib_attach(device_t dev)
 	}
 
 	rid = 2;
-	sc->cfg_mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
-	    RF_ALLOCATED);
+	sc->cfg_mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, 0);
 	if (sc->cfg_mem_res == NULL) {
 		device_printf(dev, "Cannot allocate config space memory\n");
 		rv = ENXIO;

sys/x86/iommu/amd_drv.c

@@ -494,7 +494,7 @@ amdiommu_attach(device_t dev)
 	}
 	sc->mmio_res = bus_alloc_resource(dev, SYS_RES_MEMORY, &sc->mmio_rid,
 	    sc->mmio_base, sc->mmio_base + sc->mmio_sz - 1, sc->mmio_sz,
-	    RF_ALLOCATED | RF_ACTIVE | RF_SHAREABLE);
+	    RF_ACTIVE | RF_SHAREABLE);
 	if (sc->mmio_res == NULL) {
 		device_printf(dev,
 		    "bus_alloc_resource %#jx-%#jx failed\n",