ARM: 7074/1: gpio: davinci: eliminate unused variable warnings

Since commit 5093aec8
"arm: davinci: Cleanup irq chip code", the variable 'mask' and 'g'
are not being used.

This patch eliminate below unused variable warnings:

  CC      drivers/gpio/gpio-davinci.o
drivers/gpio/gpio-davinci.c: In function 'gpio_irq_type':
drivers/gpio/gpio-davinci.c:234: warning: unused variable 'mask'
drivers/gpio/gpio-davinci.c:233: warning: unused variable 'g'

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>