scsi: scsi_dh_alua: Fix signedness bug in alua_rtpg()

The "retval" variable needs to be signed for the error handling to work.

Link: https://lore.kernel.org/r/YLjMEAFNxOas1mIp@mwanda
Fixes: 7e26e3ea0287 ("scsi: scsi_dh_alua: Check for negative result value")
Reviewed-by: Martin Wilck <[e-mail]>
Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/device_handler/scsi_dh_alua.c

···
 	int len, k, off, bufflen = ALUA_RTPG_SIZE;
 	int group_id_old, state_old, pref_old, valid_states_old;
 	unsigned char *desc, *buff;
-	unsigned err, retval;
+	unsigned err;
+	int retval;
 	unsigned int tpg_desc_tbl_off;
 	unsigned char orig_transition_tmo;
 	unsigned long flags;