CPU Overclock: initial overclock for Krait 600 (1.7 GHz variants)

overclocking up to 2.1 GHz

Signed-off-by: Paul Reioux <reioux@gmail.com>

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 Low CPU Clocks: Allow ultra low CPU frequencies for better battery performance

while screen is on or background operations like audio books and music

Signed-off-by: Paul Reioux <reioux@gmail.com>