tty: serial: bcm63xx_uart: define UART_REG_SIZE constant

The bcm63xx_uart driver uses RSET_UART_SIZE which is a constant defined
for MIPS-based BCM63xx platforms, pull this constant value from the
MIPS-specific header and put it in include/linux/serial_bcm63xx.h to
make the driver platform agnostic.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/tty/serial/bcm63xx_uart.c
Simple merge

diff --cc include/linux/serial_bcm63xx.h
Simple merge