Fix MISRA Rule 5.3 Part 2

Use a _ prefix for Macro arguments to prevent that argument from
hiding variables of the same name in the outer scope

Rule 5.3: An identifier declared in an inner scope shall not
          hide an identifier declared in an outer scope

Fixed For:
    make LOG_LEVEL=50 PLAT=fvp

Change-Id: I67b6b05cbad4aeca65ce52981b4679b340604708
Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
diff --git a/drivers/arm/smmu/smmu_v3.c b/drivers/arm/smmu/smmu_v3.c
index cfe8c2a..7b017e3 100644
--- a/drivers/arm/smmu/smmu_v3.c
+++ b/drivers/arm/smmu/smmu_v3.c
@@ -8,8 +8,8 @@
 #include <smmu_v3.h>
 
 /* Test for pending invalidate */
-#define INVAL_PENDING(base)	\
-	smmuv3_read_s_init(base) & SMMU_S_INIT_INV_ALL_MASK
+#define INVAL_PENDING(_base)	\
+	smmuv3_read_s_init(_base) & SMMU_S_INIT_INV_ALL_MASK
 
 static inline uint32_t smmuv3_read_s_idr1(uintptr_t base)
 {