serial: imx: add wrappers for writel and readl

This prepares implementing shadow copies for the control registers and
additionally provides a good place to hook in debug code to trace
register usage.

Most of this patch was done using pattern substitution:

	perl -p -i -e '
		s/\breadl(?:_relaxed)?\((?:sport->port\.|port->)membase \+/imx_uart_readl(sport,/;
		s/\bwritel(?:_relaxed)?\(([^,]*), (sport->port\.|port->)membase \+/imx_uart_writel(sport, $1,/;
	' drivers/tty/serial/imx.c

Signed-off-by: Uwe Kleine-König <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Uwe Kleine-König