clk: at91: Migrate to clk_hw based registration and OF APIs

clk: at91: 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 in this driver, allowing us to
move closer to a clear split of consumer and provider clk APIs.

Signed-off-by: Stephen Boyd <[email protected]>
Acked-by: Alexandre Belloni <[email protected]>
Tested-by: Alexandre Belloni <[email protected]>
Acked-by: Boris Brezillon <[email protected]>
Signed-off-by: Stephen Boyd <[email protected]>