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 <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/ptp/ptp_kvm_x86.c

···
 	long ret;
 
 	if (!kvm_para_available())
-		return -ENODEV;
+		return -EOPNOTSUPP;
 
 	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) {
 		p = alloc_page(GFP_KERNEL | __GFP_ZERO);
···
 
 	clock_pair_gpa = slow_virt_to_phys(clock_pair);
 	if (!pvclock_get_pvti_cpu0_va()) {
-		ret = -ENODEV;
+		ret = -EOPNOTSUPP;
 		goto err;
 	}
 
 	ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
 			     KVM_CLOCK_PAIRING_WALLCLOCK);
 	if (ret == -KVM_ENOSYS) {
-		ret = -ENODEV;
+		ret = -EOPNOTSUPP;
 		goto err;
 	}