ptp: Properly handle compat ioctls

ptp: Properly handle compat ioctls

Pointer arguments passed to ioctls need to pass through compat_ptr() to
work correctly on s390; as explained in Documentation/driver-api/ioctl.rst.
Detect compat mode at runtime and call compat_ptr() for those commands
which do take pointer arguments.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/1ba5d3a4-7931-455b-a3ce-85a968a7cb10@app.fastmail.com/
Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://patch.msgid.link/20250125-posix-clock-compat_ioctl-v2-1-11c865c500eb@weissschuh.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>