KVM: x86/mmu: Collapse kvm_flush_remote_tlbs_with_{range,address}() together

KVM: x86/mmu: Collapse kvm_flush_remote_tlbs_with_{range,address}() together

Collapse kvm_flush_remote_tlbs_with_range() and
kvm_flush_remote_tlbs_with_address() into a single function. This
eliminates some lines of code and a useless NULL check on the range
struct.

Opportunistically switch from ENOTSUPP to EOPNOTSUPP to make checkpatch
happy.

Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20230126184025.2294823-4-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>