ARMv8: make master CPU checking logic more clear

macro branch_if_master checks master CPU via (Aff3 & (Aff2:Aff1:Aff0))
it is simple but a little obscure.

fix by checking Affx fields within MPIDR_EL1 directly.
Signed-off-by: Nzijun_hu <zijun_hu@htc.com>

arch/arm/include/asm/macro.h

@@ -131,6 +131,7 @@ lr	.req	x30
 	/* NOTE: MPIDR handling will be erroneous on multi-cluster machines */
 	mrs	\xreg1, mpidr_el1
 	lsr	\xreg2, \xreg1, #32
+	lsl	\xreg2, \xreg2, #32
 	lsl	\xreg1, \xreg1, #40
 	lsr	\xreg1, \xreg1, #40
 	orr	\xreg1, \xreg1, \xreg2