msm: kgsl: augment GPUOC config variable

Provide the enduser with a wider choice:
MSM_KGSL_GPUOC_STOCK = 3D@266, 2D@200
MSM_KGSL_GPUOC_NORM = 3D@300, 2D@228
MSM_KGSL_GPUOC_MAX = 3D@320 & 2D@266 + Bandwith pushed

This will decrease the need of changing the source code
drastically.

Conflicts:

	arch/arm/configs/JMB_defconfig
	arch/arm/mach-msm/Kconfig
	arch/arm/mach-msm/clock-8x60.c
	arch/arm/mach-msm/devices-msm8x60.c