refactor(qemu-sbsa): rename function sip_svc_init() to something more meaningful

There is no relation between the name of function sip_svc_init() and
what it does.  As such rename it to something more appropriate and move
it to a header that make sense.

No change in functionality.

Change-Id: I7bd78b1fe70e2930c395ef0a097bfad3b1e55d3a
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
diff --git a/plat/qemu/common/qemu_bl31_setup.c b/plat/qemu/common/qemu_bl31_setup.c
index 33354dc..c047640 100644
--- a/plat/qemu/common/qemu_bl31_setup.c
+++ b/plat/qemu/common/qemu_bl31_setup.c
@@ -14,6 +14,9 @@
 #if ENABLE_RME
 #include <qemu_pas_def.h>
 #endif
+#ifdef PLAT_qemu_sbsa
+#include <sbsa_platform.h>
+#endif
 
 #include "qemu_private.h"
 
@@ -66,7 +69,7 @@
 
 /* Platform names have to be lowercase. */
 #ifdef PLAT_qemu_sbsa
-	sip_svc_init();
+	sbsa_platform_init();
 #endif
 
 	/*