plat: xilinx: versal: Remove cortex-a53 compilation

Versal is a72 based that's why there is no reason to build low level
assemble code for a53.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Change-Id: Iff9cf2582102d951825b87fd9af18e831ca717d6

plat/xilinx/versal/platform.mk

@@ -60,7 +60,6 @@ PLAT_BL_COMMON_SOURCES	:=	lib/xlat_tables/xlat_tables_common.c		\
 				plat/xilinx/versal/aarch64/versal_common.c
 
 BL31_SOURCES		+=	drivers/arm/cci/cci.c				\
-				lib/cpus/aarch64/cortex_a53.S			\
 				lib/cpus/aarch64/cortex_a72.S			\
 				plat/common/plat_psci_common.c			\
 				plat/xilinx/common/ipi.c			\