clk: imx: clk-pfd: Switch to clk_hw based API

Switch the imx_clk_pfd function to clk_hw based API, rename accordingly
and add a macro for clk based legacy. This allows us to move closer to
a clear split between consumer and provider clk APIs.

Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>