gnss: ubx: make struct ubx_gserial_ops static

The structure ubx_gserial_ops is local to the source and does not need
to be in global scope, so make it static.

Cleans up sparse warning:
symbol 'ubx_gserial_ops' was not declared. Should it be static?
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NJohan Hovold <johan@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gnss/ubx.c

@@ -59,7 +59,7 @@ static int ubx_set_power(struct gnss_serial *gserial,
 	return -EINVAL;
 }
 
-const struct gnss_serial_ops ubx_gserial_ops = {
+static const struct gnss_serial_ops ubx_gserial_ops = {
 	.set_power = ubx_set_power,
 };