hw/isa: Introduce a CONFIG_ISA_SUPERIO switch for isa-superio.c

Currently, isa-superio.c is always compiled as soon as CONFIG_ISA_BUS
is enabled. But there are also machines that have an ISA BUS without
any of the superio chips attached to it, so we should not compile
isa-superio.c in case we only compile a QEMU for such a machine.
Thus add a proper CONFIG_ISA_SUPERIO switch so that this file only gets
compiled when we really, really need it.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/isa/Kconfig

@@ -13,9 +13,13 @@ config I82378
     select MC146818RTC
     select PCSPK
 
-config PC87312
+config ISA_SUPERIO
     bool
     select ISA_BUS
+
+config PC87312
+    bool
+    select ISA_SUPERIO
     select I8259
     select I8254
     select I8257
@@ -34,14 +38,14 @@ config PIIX4
 
 config VT82C686
     bool
-    select ISA_BUS
+    select ISA_SUPERIO
     select ACPI_SMBUS
     select SERIAL_ISA
     select FDC
 
 config SMC37C669
     bool
-    select ISA_BUS
+    select ISA_SUPERIO
     select SERIAL_ISA
     select PARALLEL
     select FDC

hw/isa/Makefile.objs

@@ -1,5 +1,5 @@
 common-obj-$(CONFIG_ISA_BUS) += isa-bus.o
-common-obj-$(CONFIG_ISA_BUS) += isa-superio.o
+common-obj-$(CONFIG_ISA_SUPERIO) += isa-superio.o
 common-obj-$(CONFIG_APM) += apm.o
 common-obj-$(CONFIG_I82378) += i82378.o
 common-obj-$(CONFIG_PC87312) += pc87312.o

hw/mips/Kconfig

@@ -13,6 +13,7 @@ config R4K
 
 config MALTA
     bool
+    select ISA_SUPERIO
 
 config MIPSSIM
     bool