AArch32: Add support to PSCI lib

This patch adds AArch32 support to PSCI library, as follows :

* The `psci_helpers.S` is implemented for AArch32.

* AArch32 version of internal helper function `psci_get_ns_ep_info()` is
  defined.

* The PSCI Library is responsible for the Non Secure context initialization.
  Hence a library interface `psci_prepare_next_non_secure_ctx()` is introduced
  to enable EL3 runtime firmware to initialize the non secure context without
  invoking context management library APIs.

Change-Id: I25595b0cc2dbfdf39dbf7c589b875cba33317b9d
diff --git a/lib/psci/psci_setup.c b/lib/psci/psci_setup.c
index d35e000..20d0635 100644
--- a/lib/psci/psci_setup.c
+++ b/lib/psci/psci_setup.c
@@ -278,3 +278,15 @@
 	/* Initialize the cpu_ops pointer. */
 	init_cpu_ops();
 }
+
+/******************************************************************************
+ * PSCI Library interface to initialize the cpu context for the next non
+ * secure image during cold boot. The relevant registers in the cpu context
+ * need to be retrieved and programmed on return from this interface.
+ *****************************************************************************/
+void psci_prepare_next_non_secure_ctx(entry_point_info_t *next_image_info)
+{
+	assert(GET_SECURITY_STATE(next_image_info->h.attr) == NON_SECURE);
+	cm_init_my_context(next_image_info);
+	cm_prepare_el3_exit(NON_SECURE);
+}