KVM: SVM: Drop "always" flag from list of possible passthrough MSRs

KVM: SVM: Drop "always" flag from list of possible passthrough MSRs

Drop the "always" flag from the array of possible passthrough MSRs, and
instead manually initialize the permissions for the handful of MSRs that
KVM passes through by default.  In addition to cutting down on boilerplate
copy+paste code and eliminating a misleading flag (the MSRs aren't always
passed through, e.g. thanks to MSR filters), this will allow for removing
the direct_access_msrs array entirely.

Link: https://lore.kernel.org/r/20250610225737.156318-17-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>