zynqmp: Define ep config for ZynqMP

Define a new config "zynqmp_ep" for ZynqMP instead
of xilinx_zynqmp. This defconfig supports all emulation
platforms of ZynqMP. Also renamed TARGET_XILINX_ZYNQMP
to ARCH_ZYNQMP.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/arm/cpu/armv8/Makefile b/arch/arm/cpu/armv8/Makefile
index dee5e25..6466ebb 100644
--- a/arch/arm/cpu/armv8/Makefile
+++ b/arch/arm/cpu/armv8/Makefile
@@ -16,4 +16,4 @@
 obj-y	+= transition.o
 
 obj-$(CONFIG_FSL_LSCH3) += fsl-lsch3/
-obj-$(CONFIG_TARGET_XILINX_ZYNQMP) += zynqmp/
+obj-$(CONFIG_ARCH_ZYNQMP) += zynqmp/