KVM: x86: Hoist x86.c's global msr_* variables up above kvm_do_msr_access()

Move the definitions of the various MSR arrays above kvm_do_msr_access()
so that kvm_do_msr_access() can query the arrays when handling failures,
e.g. to squash errors if userspace tries to read an MSR that isn't fully
supported, but that KVM advertised as being an MSR-to-save.

No functional change intended.

Link: https://lore.kernel.org/r/20240802181935.292540-9-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>