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>

The driver has only one API: to initialize an SMMUv3 device. This
operates on a device that implements secure state, by invalidating
secure caches and TLBs.

Change-Id: Ief32800419ddf0f1fe38c8f0da8f5ba75c72c826
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>