refactor(lib/realm): rename realm states according to spec

Rename the REALM_STATE_* defines to REALM_* to comply with the names in
the RMM specification.

Change-Id: I22e730b3c07a4600ee96d4569e3319e0a8e1f68d
Signed-off-by: Mate Toth-Pal <mate.toth-pal@arm.com>
diff --git a/runtime/rsi/psci.c b/runtime/rsi/psci.c
index 4769e36..1b42da1 100644
--- a/runtime/rsi/psci.c
+++ b/runtime/rsi/psci.c
@@ -231,7 +231,7 @@
 	rd = granule_map(rec->realm_info.g_rd, SLOT_RD);
 	assert(rd != NULL);
 
-	set_rd_state(rd, REALM_STATE_SYSTEM_OFF);
+	set_rd_state(rd, REALM_SYSTEM_OFF);
 
 	buffer_unmap(rd);
 	granule_unlock(g_rd);