ipmi:ssif: Add missing unlock in error branch

When getting flags, a response to a different message would
result in a deadlock because of a missing unlock.  Add that
unlock and a comment.  Found by static analysis.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable@vger.kernel.org # 3.19
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_ssif.c

@@ -766,6 +766,11 @@ static void msg_done_handler(struct ssif_info *ssif_info, int result,
 			       result, len, data[2]);
 		} else if (data[0] != (IPMI_NETFN_APP_REQUEST | 1) << 2
 			   || data[1] != IPMI_GET_MSG_FLAGS_CMD) {
+			/*
+			 * Don't abort here, maybe it was a queued
+			 * response to a previous command.
+			 */
+			ipmi_ssif_unlock_cond(ssif_info, flags);
 			pr_warn(PFX "Invalid response getting flags: %x %x\n",
 				data[0], data[1]);
 		} else {