omap: CONFIG_ISP1301_OMAP redefined in Beagle defconfig

The symbol CONFIG_ISP1301_OMAP was defined twice in the
defconfig. This was causing the warning:
arch/arm/configs/omap3_beagle_defconfig:972:warning:
 override: reassigning to symbol ISP1301_OMAP

Signed-off-by: Sanjeev Premi <premi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>