Use resource_size_t for serial port IO addresses

At present, various parts of the serial code use unsigned long to define
resource addresses.  This is a problem, because some 32-bit platforms have
physical addresses larger than 32-bits, and have mmio serial uarts located
above the 4GB point.

This patch changes the type of mapbase in both struct uart_port and struct
plat_serial8250_port to resource_size_t, which can be configured to be 64
bits on such platforms.  The mapbase in serial_struct can't safely be
changed, because that structure is user visible.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>