This patch prepares the mcp251xfd_chip_clock_init() function for PLL
support.

If the PLL is needed is must be switched on after chip reset. This
should be done in the mcp251xfd_chip_clock_init() function. Prepare
this function to wait for the OSC and PLL to be ready.

Link: https://lore.kernel.org/all/20220207131047.282110-14-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>