tty: serial: fsl_lpuart: move the lpuart32_int() below

Move the lpuart32_int() below lpuart_copy_rx_to_tty(), this is a
preparation patch for the next patch to avoid the function declaration,
no actual functional changes.

Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20230710013857.7396-2-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>