ARM platforms: Provide SDEI entry point validation

Provide a strong definition for plat_sdei_validate_sdei_entrypoint()
which translates client address to Physical Address, and then validating
the address to be present in DRAM.

Change-Id: Ib93eb66b413d638aa5524d1b3de36aa16d38ea11
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/include/lib/aarch64/arch_helpers.h b/include/lib/aarch64/arch_helpers.h
index 9c022ab..782343d 100644
--- a/include/lib/aarch64/arch_helpers.h
+++ b/include/lib/aarch64/arch_helpers.h
@@ -155,6 +155,7 @@
 DEFINE_SYSOP_TYPE_PARAM_FUNC(at, s12e1w)
 DEFINE_SYSOP_TYPE_PARAM_FUNC(at, s12e0r)
 DEFINE_SYSOP_TYPE_PARAM_FUNC(at, s12e0w)
+DEFINE_SYSOP_TYPE_PARAM_FUNC(at, s1e2r)
 
 void flush_dcache_range(uintptr_t addr, size_t size);
 void clean_dcache_range(uintptr_t addr, size_t size);