clk: imx: Rename sccg and frac pll register to suggest clk_hw

Renaming the imx_clk_frac_pll and imx_clk_sccg_pll register functions to
imx_clk_hw_frac_pll, respectively imx_clk_hw_sccg_pll to be more obvious
that they are clk_hw based.

Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>