serial: imx: Use RX_BUF_SIZE to set size of RX buffer
The imx serial driver uses PAGE_SIZE when allocating rx_buf, but then
uses RX_BUF_SIZE (which is currently defined as PAGE_SIZE) to describe
the length of the buffer when initialising the scatter gather list.
In order to ensure that this stays consistent, use RX_BUF_SIZE in both
locations.
Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
Acked-by: Uwe Kleine-König <u.kleine-könig@pengtronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>