ptp: kvm: x86: Return EOPNOTSUPP instead of ENODEV from kvm_arch_ptp_init()

ptp: kvm: x86: Return EOPNOTSUPP instead of ENODEV from kvm_arch_ptp_init()

The caller, ptp_kvm_init(), emits a warning if kvm_arch_ptp_init() exits
with any error which is not EOPNOTSUPP:

	"fail to initialize ptp_kvm"

Replace ENODEV with EOPNOTSUPP to avoid this spurious warning,
aligning with the ARM implementation.

Fixes: a86ed2cfa13c ("ptp: Don't print an error if ptp_kvm is not supported")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://patch.msgid.link/20241203-kvm_ptp-eopnotsuppp-v2-1-d1d060f27aa6@weissschuh.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>