SMMUv3: refactor the driver code

This patch is a preparation for the subsequent changes in
SMMUv3 driver. It introduces a new "smmuv3_poll" function
and replaces inline functions for accessing SMMU registers
with mmio read/write operations. Also the infinite loop
for the poll has been replaced with a counter based timeout.

Change-Id: I7a0547beb1509601f253e126b1a7a6ab3b0307e7
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
diff --git a/plat/arm/board/fvp/fvp_bl31_setup.c b/plat/arm/board/fvp/fvp_bl31_setup.c
index 7f28b20..3f92d37 100644
--- a/plat/arm/board/fvp/fvp_bl31_setup.c
+++ b/plat/arm/board/fvp/fvp_bl31_setup.c
@@ -34,7 +34,7 @@
 	 */
 	fvp_interconnect_enable();
 
-	/* On FVP RevC, intialize SMMUv3 */
+	/* On FVP RevC, initialize SMMUv3 */
 	if ((arm_config.flags & ARM_CONFIG_FVP_HAS_SMMUV3) != 0U)
 		smmuv3_init(PLAT_FVP_SMMUV3_BASE);
 }