arm64: Have get_kernel_reg return void

It now panics when it's unable to find the register, so doesn't need
to return a status.

Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D55106

sys/arm64/arm64/identcpu.c

@@ -2514,7 +2514,7 @@ mrs_field_cmp(uint64_t a, uint64_t b, u_int shift, int width, bool sign)
 	return (a - b);
 }
 
-bool
+void
 get_kernel_reg_iss(u_int iss, uint64_t *val)
 {
 	int i;
@@ -2522,7 +2522,7 @@ get_kernel_reg_iss(u_int iss, uint64_t *val)
 	for (i = 0; i < nitems(user_regs); i++) {
 		if (user_regs[i].iss == iss) {
 			*val = CPU_DESC_FIELD(kern_cpu_desc, i);
-			return (true);
+			return;
 		}
 	}
 
@@ -2533,7 +2533,7 @@ get_kernel_reg_iss(u_int iss, uint64_t *val)
  * Fetch the specified register's value, ensuring that individual field values
  * do not exceed those in the mask.
  */
-bool
+void
 get_kernel_reg_iss_masked(u_int iss, uint64_t *valp, uint64_t mask)
 {
 	const struct mrs_field *fields;
@@ -2549,7 +2549,7 @@ get_kernel_reg_iss_masked(u_int iss, uint64_t *valp, uint64_t mask)
 				    fields[j].shift, fields[j].sign);
 			}
 			*valp = mask;
-			return (true);
+			return;
 		}
 	}
 

sys/arm64/include/cpu.h

@@ -282,10 +282,10 @@ void	update_special_regs(u_int);
 void	update_special_reg_iss(u_int, uint64_t, uint64_t);
 #define	update_special_reg(reg, clear, set)			\
     update_special_reg_iss(reg ## _ISS, clear, set)
-bool	get_kernel_reg_iss(u_int, uint64_t *);
+void	get_kernel_reg_iss(u_int, uint64_t *);
 #define	get_kernel_reg(reg, valp)				\
     get_kernel_reg_iss(reg ## _ISS, valp)
-bool	get_kernel_reg_iss_masked(u_int, uint64_t *, uint64_t);
+void	get_kernel_reg_iss_masked(u_int, uint64_t *, uint64_t);
 #define	get_kernel_reg_masked(reg, valp, mask)			\
     get_kernel_reg_iss_masked(reg ## _ISS, valp, mask)
 bool	get_user_reg_iss(u_int, uint64_t *, bool);