Fix typo in assert string.

Change-Id: I50b173f0d64644ccf40a924e3a79e7f1546066e0
diff --git a/src/ffa_memory.c b/src/ffa_memory.c
index aeea137..07a3842 100644
--- a/src/ffa_memory.c
+++ b/src/ffa_memory.c
@@ -41,7 +41,7 @@
 	      "struct ffa_composite_memory_region must be a multiple of 16 "
 	      "bytes long.");
 static_assert(sizeof(struct ffa_memory_region_attributes) == 4,
-	      "struct ffa_memory_region_attributes must be 4bytes long.");
+	      "struct ffa_memory_region_attributes must be 4 bytes long.");
 static_assert(sizeof(struct ffa_memory_access) % 16 == 0,
 	      "struct ffa_memory_access must be a multiple of 16 bytes long.");
 static_assert(sizeof(struct ffa_memory_region) % 16 == 0,