mtd: cfi_cmdset_0002: Avoid walking all chips when unlocking.

BugLink: https://bugs.launchpad.net/bugs/1784382

commit f1ce87f6 upstream.

cfi_ppb_unlock() walks all flash chips when unlocking sectors,
avoid walking chips unaffected by the unlock operation.

Fixes: 1648eaaa ("mtd: cfi_cmdset_0002: Support Persistent Protection Bits (PPB) locking")
Cc: stable@vger.kernel.org
Signed-off-by: Joakim Tjernlund <joakim.tjernlund@infinera.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/mtd/chips/cfi_cmdset_0002.c

@@ -2683,6 +2683,8 @@ static int __maybe_unused cfi_ppb_unlock(struct mtd_info *mtd, loff_t ofs,
 			i++;
 
 		if (adr >> cfi->chipshift) {
+			if (offset >= (ofs + len))
+				break;
 			adr = 0;
 			chipnum++;