ARM: 5972/1: nomadik-gpio: convert to platform driver

ARM: 5972/1: nomadik-gpio: convert to platform driver

On the U8500 platform there are four GPIO blocks, each with a 4K address
space, including the peripheral identification.  However, each of these
blocks have a varying number of banks, each of which have 32 GPIOs and
an interrupt line.

The current nomadik-gpio driver implementation can handle each of these
sub-banks easily with one instance each, but cannot as-is be hooked up
to them because it is an AMBA driver and it expects to see a peripheral
with the appropriate peripheral ids but having only one bank and only
one interrupt.

Solve this by converting the driver to a platform driver.

Acked-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>