pch_uart : fix warnings for 64bit compile

Fix the following warnings
drivers/serial/pch_uart.c: In function ‘dma_handle_rx’:
drivers/serial/pch_uart.c:685:24: warning: cast from pointer to integer of different size
drivers/serial/pch_uart.c: In function ‘dma_handle_tx’:
drivers/serial/pch_uart.c:778:23: warning: cast from pointer to integer of different size
drivers/serial/pch_uart.c: In function ‘pch_uart_init_port’:
drivers/serial/pch_uart.c:1289:20: warning: cast to pointer from integer of different size
drivers/serial/pch_uart.c: In function ‘pch_uart_exit_port’:
drivers/serial/pch_uart.c:1328:2: warning: cast from pointer to integer of different size

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Reported-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>