mei: bus: type promotion bug in mei_fwver()

if __mei_cl_recv() returns a negative then "bytes_recv"
type is promoted to a high positive value in comparison with
size_t evaluated by MKHI_FWVER_LEN(1). It results in error condition
not to be detected.

Cc: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 9078ad92ef86 ("mei: expose fw version to sysfs")
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/bus-fixup.c

@@ -181,7 +181,7 @@ static int mei_fwver(struct mei_cl_device *cldev)
 	ret = 0;
 	bytes_recv = __mei_cl_recv(cldev->cl, buf, sizeof(buf), 0,
 				   MKHI_RCV_TIMEOUT);
-	if (bytes_recv < MKHI_FWVER_LEN(1)) {
+	if (bytes_recv < 0 || bytes_recv < MKHI_FWVER_LEN(1)) {
 		/*
 		 * Should be at least one version block,
 		 * error out if nothing found