Core support code for CPU frequency changes, which will be used by
the generic cpufreq driver.

The register view is different from the generic clk-mux; it has
a separate status register, and an update bit to load the register
setting.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>