omap3: Increase limit on bootarg 'mpurate'

The value of mpurate is currently expected to be less
than 1000 when specified in MHz.

This patch raises this limit to 2000 to support 1GHz
capable processors. The new limit should be reasonable
for quite some time.

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
OMAP2+: cpufreq: support clamping initial max frequency to board-provided value

This is useful to allow boards to define "overclocking" OPPs without
having them be automatically enabled when the cpufreq driver loads.

Change-Id: I29d94981d3827280d8b1bc4cd11dc60f8de14db7
add nominal cpu freq