feat(zynqmp): add hooks for mmap and early setup

Add early setup hooks (via custom_early_setup()) and provide a way
to cover custom memory mapping which includes extending memory map
via custom_mmap_add().

This likely also require to align MAX_XLAT_TABLE, MAX_XLAT_TABLES
macros. It can be done for example by defining these macros in
custom_pkg.mk
MAX_MMAP_REGIONS	:= XY
$(eval $(call add_define,MAX_MMAP_REGIONS))
MAX_XLAT_TABLES		:= XZ
$(eval $(call add_define,MAX_XLAT_TABLES))

custom_early_setup() can be used for early low level operations
related to setting up the system to correct state.

Signed-off-by: Amit Nagal <amit.nagal@amd.com>
Change-Id: I61df6f9ba5af0bc97c430974fb10a2edde44f23d
diff --git a/plat/xilinx/zynqmp/custom_sip_svc.c b/plat/xilinx/zynqmp/custom_sip_svc.c
index 459aa39..fbb0a33 100644
--- a/plat/xilinx/zynqmp/custom_sip_svc.c
+++ b/plat/xilinx/zynqmp/custom_sip_svc.c
@@ -15,3 +15,11 @@
 	WARN("Unimplemented SiP Service Call: 0x%x\n", smc_fid);
 	SMC_RET1(handle, SMC_UNK);
 }
+
+void custom_early_setup(void)
+{
+}
+
+void custom_mmap_add(void)
+{
+}