ARM: mvebu: prefix coprocessor operand with p

In every other instance where mrc is used the coprocessor operand
is prefix with p (e.g. p15). Use the p prefix in this case too.
This fixes a build issue when using LLVM's integrated assembler:
  arch/arm/mach-mvebu/coherency_ll.S:69:6: error: invalid operand for instruction
   mrc 15, 0, r3, cr0, cr0, 5
       ^
  arch/arm/mach-mvebu/pmsu_ll.S:19:6: error: invalid operand for instruction
   mrc 15, 0, r0, cr0, cr0, 5 @ get the CPU ID
       ^
Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>

arch/arm/mach-mvebu/coherency_ll.S

@@ -66,7 +66,7 @@ ENDPROC(ll_get_coherency_base)
  * fabric registers
  */
 ENTRY(ll_get_coherency_cpumask)
-	mrc	15, 0, r3, cr0, cr0, 5
+	mrc	p15, 0, r3, cr0, cr0, 5
 	and	r3, r3, #15
 	mov	r2, #(1 << 24)
 	lsl	r3, r2, r3

arch/arm/mach-mvebu/pmsu_ll.S

@@ -16,7 +16,7 @@
 ENTRY(armada_38x_scu_power_up)
 	mrc     p15, 4, r1, c15, c0	@ get SCU base address
 	orr	r1, r1, #0x8		@ SCU CPU Power Status Register
-	mrc	15, 0, r0, cr0, cr0, 5	@ get the CPU ID
+	mrc	p15, 0, r0, cr0, cr0, 5	@ get the CPU ID
 	and	r0, r0, #15
 	add	r1, r1, r0
 	mov	r0, #0x0