ARM: Next round of cleanup in swtch-v*.S.

- remove now useless #if __ARM_ARCH conditional
 - use macro for accessing CP15 registers
 - remove unused PCPU_SIZE

Pointed by: kib

sys/arm/arm/swtch-v4.S

@@ -99,7 +99,6 @@ __FBSDID("$FreeBSD$");
 
 .Lcurpcpu:
 	.word   _C_LABEL(__pcpu)
-	.word	PCPU_SIZE
 .Lblocked_lock:
 	.word	_C_LABEL(blocked_lock)
 

sys/arm/arm/swtch-v6.S

@@ -85,13 +85,14 @@
 #include <machine/asm.h>
 #include <machine/asmacros.h>
 #include <machine/armreg.h>
+#include <machine/sysreg.h>
 #include <machine/vfp.h>
 
 __FBSDID("$FreeBSD$");
 
-#if __ARM_ARCH >= 6 && defined(SMP)
+#if defined(SMP)
 #define GET_PCPU(tmp, tmp2) \
-	mrc 	p15, 0, tmp, c0, c0, 5;	\
+	mrc 	CP15_MPIDR(tmp);	\
 	and	tmp, tmp, #0xf;		\
 	ldr 	tmp2, .Lcurpcpu+4;	\
 	mul 	tmp, tmp, tmp2;		\
@@ -113,9 +114,6 @@ __FBSDID("$FreeBSD$");
 .Lblocked_lock:
 	.word	_C_LABEL(blocked_lock)
 
-
-#include <machine/sysreg.h>
-
 ENTRY(cpu_context_switch) /* QQQ: What about macro instead of function?	*/
 	DSB
 	mcr	CP15_TTBR0(r0)		/* set the new TTB */