ptp: ptp_ines: use new PTP_MSGTYPE_* define(s)

Remove driver internal defines for this. Masking msgtype with 0xf is
already done within ptp_get_msgtype().

Signed-off-by: Christian Eggers <ceggers@arri.de>
Cc: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>