xlat: Define translation regime in AArch32

Previously, in AArch32, `IMAGE_XLAT_DEFAULT_REGIME` wasn't defined. The
translation regime is only used in the AArch64 port of the translation
tables library v2, so this is not a problem for now, but future patches
will use it.

`IMAGE_EL` isn't used in AArch32, so it isn't needed to define it.

Change-Id: I4acdb01a58658956ab94bd82ed5b7fee1aa6ba90
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

include/lib/xlat_tables/xlat_tables_v2_helpers.h

@@ -162,8 +162,12 @@ struct xlat_ctx {
 		.initialized = 0,						\
 	}
 
+#if AARCH64
 
-/* This IMAGE_EL macro must not to be used outside the library */
+/*
+ * This IMAGE_EL macro must not to be used outside the library, and it is only
+ * used in AArch64.
+ */
 #if IMAGE_BL1 || IMAGE_BL31
 # define IMAGE_EL	3
 # define IMAGE_XLAT_DEFAULT_REGIME EL3_REGIME
@@ -172,6 +176,17 @@ struct xlat_ctx {
 # define IMAGE_XLAT_DEFAULT_REGIME EL1_EL0_REGIME
 #endif
 
+#else /* if AARCH32 */
+
+/*
+ * The PL1&0 translation regime in AArch32 behaves like the EL1&0 regime in
+ * AArch64 except for the XN bits, but we set and unset them at the same time,
+ * so there's no difference in practice.
+ */
+#define IMAGE_XLAT_DEFAULT_REGIME EL1_EL0_REGIME
+
+#endif /* AARCH64 */
+
 #endif /*__ASSEMBLY__*/
 
 #endif /* __XLAT_TABLES_V2_HELPERS_H__ */