KVM: Remove unused kvm_make_cpus_request_mask() declaration

KVM: Remove unused kvm_make_cpus_request_mask() declaration

Commit 7ee30bc132c6 ("KVM: x86: deliver KVM IOAPIC scan request to target
vCPUs") declared but never implemented kvm_make_cpus_request_mask() as
kvm_make_vcpus_request_mask() already existed.

Note, KVM's APIs are painfully inconsistent, as the inclusive variant uses
"vcpus", whereas the exclusive/all variants use "cpus", which is likely
what led to the spurious declaration.  The "vcpus" terminology is more
correct, especially since the helpers will kick _physical_ CPUs by calling
kvm_kick_many_cpus().  But that's a cleanup for the future.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20230814140339.47732-1-yuehaibing@huawei.com
[sean: split to separate patch, call out inconsistent naming]
Signed-off-by: Sean Christopherson <seanjc@google.com>