serial: pmac_zilog: Drop usage of platform_driver_probe()

There are considerations to drop platform_driver_probe() as a concept
that isn't relevant any more today. It comes with an added complexity
that makes many users hold it wrong. (E.g. this driver should have
marked the driver struct with __refdata to prevent the below mentioned
false positive section mismatch warning.)

This fixes a W=1 build warning:

	WARNING: modpost: drivers/tty/serial/pmac_zilog: section mismatch in reference: pmz_driver+0x8 (section: .data) -> pmz_detach (section: .exit.text)

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/5ea3174616abc9fa256f115b4fb175d289ac1754.1711748999.git.u.kleine-koenig@pengutronix.de


Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>