serial: samsung: Remove redundant label

probe_err label only returns the error code. This label can be removed
and the error code can be returned directly.

Signed-off-by: Tushar Behera <tushar.b@samsung.com>
Reviewed-by: Sachin Kamat <sachin.kamat@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>