ARM: OMAP: Fix warning in gpio.c

Fix warning

arch/arm/plat-omap/gpio.c: In function '_omap_gpio_init':
arch/arm/plat-omap/gpio.c:1299: warning: unused variable 'clk_name'
arch/arm/plat-omap/gpio.c: At top level:
arch/arm/plat-omap/gpio.c:1282: warning: 'gpio_fck' defined but not used

for OMAP1.

Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>