Description of problem:
sevctl ok returns 1 on SNP capable Milan and Genoa when host kernel doesn't support SNP

Version-Release number of selected component (if applicable):
sevctl-0.4.1-2.el9.x86_64

How reproducible:
100%

Steps to Reproduce:
1. on Milan /Genoa, host kernel not support SNP

1. sevctl ok
   [ PASS ] - AMD CPU
   [ PASS ] - Microcode support
   [ PASS ] - Secure Memory Encryption (SME)
   [ PASS ] - Secure Encrypted Virtualization (SEV)
   [ PASS ] - Encrypted State (SEV-ES)
   [ FAIL ] - Secure Nested Paging (SEV-SNP)
   [ SKIP ] - VM Permission Levels
   [ SKIP ] - Number of VMPLs
   [ PASS ] - Physical address bit reduction: 6
   [ PASS ] - C-bit location: 51
   [ PASS ] - Number of encrypted guests supported simultaneously: 1006
   [ PASS ] - Minimum ASID value for SEV-enabled, SEV-ES disabled guest: 10
   [ PASS ] - SEV enabled in KVM: enabled
   [ PASS ] - SEV-ES enabled in KVM: enabled
   [ PASS ] - Reading /dev/sev: /dev/sev readable
   [ PASS ] - Writing /dev/sev: /dev/sev writable
   [ PASS ] - Page flush MSR: DISABLED
   [ PASS ] - KVM supported: API version: 12
   [ PASS ] - Memlock resource limit: Soft: 8388608 | Hard: 8388608
   Error: One or more tests in sevctl-ok reported a failure

Expected results:
sevctl return 0 on SNP capability
Additional info: