tty: serial: fsl_lpuart: count tty buffer overruns

Added support for counting the tty buffer overruns in fsl_lpuart driver
like other uart drivers.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20220111085130.5817-1-sherry.sun@nxp.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>