clk: sirf: Properly include clk.h

Clock provider drivers generally shouldn't include clk.h because
it's the consumer API. Move the include of clk.h into
clk-common.c because that's the only file that's really using
clk.h, even if it's included into the atlas6 and prima2 files.

Cc: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>