clk: bcm2835: Migrate to clk_hw based registration and OF APIs

Now that we have clk_hw based provider APIs to register clks, we
can get rid of struct clk pointers while registering clks in
these drivers, allowing us to move closer to a clear split of
consumer and provider clk APIs.

Cc: Eric Anholt <eric@anholt.net>
Cc: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>