context_mgmt: Fix MISRA defects

The macro EL_IMPLEMENTED() has been deprecated in favour of the new
function el_implemented().

Change-Id: Ic9b1b81480b5e019b50a050e8c1a199991bf0ca9
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/include/common/ep_info.h b/include/common/ep_info.h
index bf3f782..db2355a 100644
--- a/include/common/ep_info.h
+++ b/include/common/ep_info.h
@@ -30,7 +30,7 @@
 #define PARAM_EP_SECURITY_MASK		U(0x1)
 
 /* Secure or Non-secure image */
-#define GET_SECURITY_STATE(x) (x & PARAM_EP_SECURITY_MASK)
+#define GET_SECURITY_STATE(x) ((x) & PARAM_EP_SECURITY_MASK)
 #define SET_SECURITY_STATE(x, security) \
 			((x) = ((x) & ~PARAM_EP_SECURITY_MASK) | (security))