allow ION to be disabled for ARCH_MSM8X60 (eg. tenderloin)

Change Kconfig for ARCH_MSM8X60 such that auto-selection
of MSM_MULTIMEDIA_USE_ION only happens if ION is enabled.

This auto-selection prevented ION from being fully disabled
which was requested for non-android build.
msm_fb: improve backlight blank/unblank for non-android userspace
msm_fb: more gentle backlight on boot
forward port pwm_config2 from 2.6 kernel

needed for better backlight control
lcdc_lg_xga: use pwm_config2 for better backlight control
isl29023: adjust for better range (wip?)