refactor(lib/realm): remove 'lib/realm' library

This patch removes the lib/realm library by refactoring its code and
moving its components to related submodules. It also introduces two
new libraries, 'lib/granule' and 'lib/slot_buf' with sources from
'lib/realm'

Change-Id: Id41eb2da20172d8da9a5f066b3e78ec4f1a6d35d
Signed-off-by: Javier Almansa Sobrino <javier.almansasobrino@arm.com>
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
diff --git a/runtime/rsi/host_call.c b/runtime/rsi/host_call.c
index 097a8d9..bb704aa 100644
--- a/runtime/rsi/host_call.c
+++ b/runtime/rsi/host_call.c
@@ -67,7 +67,7 @@
 
 	/* Map Realm data granule to RMM address space */
 	gr = find_granule(walk_result.pa);
-	data = (uintptr_t)granule_map(gr, SLOT_RSI_CALL);
+	data = (uintptr_t)buffer_granule_map(gr, SLOT_RSI_CALL);
 	assert(data != 0UL);
 
 	host_call = (struct rsi_host_call *)(data + ipa - page_ipa);