serial: xuartps: Get rid of register access macros.
Get rid of cdns_uart_readl() and cdns_uart_writel() and just call
readl() and writel() directly.
Most of the patch was created by search-and-replace (I had to convert a
few lines manually, and break some lines longer than 80 columns):
* s/cdns_uart_readl(/readl(port->membase + /g
* s/cdns_uart_writel(\([^,]*\),/writel(\1, port->membase +/g