serial: sccnxp: Reset break and overrun bits in RX handler

This patch adds a hardware reset the break and overflow bits for
these events. Without resetting the bits they will be reported to
the core every time, when once occur.

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