clk: at91: modify PMC peripheral clock to deal with newer register layout
clk: at91: modify PMC peripheral clock to deal with newer register layout

As some more information is added to the PCR register, we'd better use
a copy of its content and modify just the peripheral-related bits.
Implement a read-modify-write for the enable() and disable() callbacks.

Signed-off-by: Nicolas Ferre <45b517be0e5ec6dc3a39715767c1d18e090d39b4@atmel.com>
Signed-off-by: Boris Brezillon <4e91513d4f418754031d3d36b3fc73980c40a38c@free-electrons.com>
Signed-off-by: Stephen Boyd <010521127f513270fe503d86ab8316ac5147f4b7@codeaurora.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs