clk: imx: pll14xx: Use FIELD_GET/FIELD_PREP

Linux has these marvelous FIELD_GET/FIELD_PREP macros for easy access
to bitfields in registers. Use them and remove the now unused *_SHIFT
defines.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Link: https://lore.kernel.org/r/20220304125256.2125023-4-s.hauer@pengutronix.de


Signed-off-by: Abel Vesa <abel.vesa@nxp.com>