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: zijun_hu <zijun_hu@htc.com>
diff --git a/arch/arm/include/asm/macro.h b/arch/arm/include/asm/macro.h
index e1916f7..0c8652a 100644
--- a/arch/arm/include/asm/macro.h
+++ b/arch/arm/include/asm/macro.h
@@ -131,6 +131,7 @@
 	/* 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