serial: sccnxp: Disable regulator on error

The patch disables the regulator in case of errors, if we have it.
In addition, the patch adds support for deferred regulator probe and
makes error path are a bit clean.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>