serial: fsl_lpuart: specify transmit FIFO size for 32-bit variant

The commit 4e8f2459 ("tty: serial: fsl_lpuart: specify transmit
FIFO size") fixed lpuart_startup only.
Fix lpuart32_startup too.

Signed-off-by: Atsushi Nemoto <atsushi.nemoto@sord.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>