KVM: selftests: Fix a typo in the vcpu_msrs_set assert

KVM: selftests: Fix a typo in the vcpu_msrs_set assert

The assert incorrectly identifies the ioctl being called.  Switch it
from KVM_GET_MSRS to KVM_SET_MSRS.

Fixes: 6ebfef83f03f ("KVM: selftest: Add proper helpers for x86-specific save/restore ioctls")
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221209201326.2781950-1-aaronlewis@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>