ice: Fix potential memory leak in ice_gnss_tty_write()

The ice_gnss_tty_write() return directly if the write_buf alloc failed,
leaking the cmd_buf.

Fix by free cmd_buf if write_buf alloc failed.

Fixes: d6b98c8d24 ("ice: add write functionality for GNSS TTY")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_gnss.c

@@ -363,6 +363,7 @@ ice_gnss_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
 	/* Send the data out to a hardware port */
 	write_buf = kzalloc(sizeof(*write_buf), GFP_KERNEL);
 	if (!write_buf) {
+		kfree(cmd_buf);
 		err = -ENOMEM;
 		goto exit;
 	}