UBIFS: rename random32() to prandom_u32()

Use more preferable function name which implies using a pseudo-random
number generator.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c
index 523bbad..52a6559 100644
--- a/fs/ubifs/tnc_commit.c
+++ b/fs/ubifs/tnc_commit.c
@@ -683,7 +683,7 @@
 		c->ilebs[c->ileb_cnt++] = lnum;
 		dbg_cmt("LEB %d", lnum);
 	}
-	if (dbg_is_chk_index(c) && !(random32() & 7))
+	if (dbg_is_chk_index(c) && !(prandom_u32() & 7))
 		return -ENOSPC;
 	return 0;
 }