can: mcp251xfd: mcp251xfd_chip_wait_for_osc_ready(): factor out into separate function

This patch factors out mcp251xfd_chip_wait_for_osc_ready() into a
separate function, it will be used in several places in the next
patches.

Link: https://lore.kernel.org/all/20220207131047.282110-7-mkl@pengutronix.de


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>