optimized screen_on_min_freq behavior

Signed-off-by: Dan Trifan <jimsth@gmail.com>

Conflicts:
	arch/arm/mach-omap2/omap2plus-cpufreq.c
omap2plus-cpufreq.c: make screen_on_min_freq, screen_off_max_freq and max_capped accessible from cpufreq.h

Signed-off-by: Dan Trifan <jimsth@gmail.com>

Conflicts:
	arch/arm/mach-omap2/omap2plus-cpufreq.c
HARDCODE SCREENON MIN FREQ to 350mhz