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/plat/hisilicon/hikey960/hikey960_bl2_setup.c b/plat/hisilicon/hikey960/hikey960_bl2_setup.c
index f57dd63..0e79e0a 100644
--- a/plat/hisilicon/hikey960/hikey960_bl2_setup.c
+++ b/plat/hisilicon/hikey960/hikey960_bl2_setup.c
@@ -191,7 +191,7 @@
 	uint32_t spsr;
 
 	/* Figure out what mode we enter the non-secure world in */
-	mode = EL_IMPLEMENTED(2) ? MODE_EL2 : MODE_EL1;
+	mode = (el_implemented(2) != EL_IMPL_NONE) ? MODE_EL2 : MODE_EL1;
 
 	/*
 	 * TODO: Consider the possibility of specifying the SPSR in