Move generic ipi_mb functions to common files

ipi_mb functions can be used for other Xilinx platform.
Move it to common file from platform specific files.

Signed-off-by: Tejas Patel <tejas.patel@xilinx.com>
Reviewed-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Jolly Shah <jollys@xilinx.com>
diff --git a/plat/xilinx/zynqmp/platform.mk b/plat/xilinx/zynqmp/platform.mk
index a4ffd6c..f0c7599 100644
--- a/plat/xilinx/zynqmp/platform.mk
+++ b/plat/xilinx/zynqmp/platform.mk
@@ -65,6 +65,7 @@
 				plat/arm/common/arm_common.c			\
 				plat/arm/common/arm_gicv2.c			\
 				plat/common/plat_gicv2.c			\
+				plat/xilinx/common/ipi.c			\
 				plat/xilinx/zynqmp/aarch64/zynqmp_helpers.S	\
 				plat/xilinx/zynqmp/aarch64/zynqmp_common.c