KVM: MIPS: Fold comparecount_func() into comparecount_wakeup()

Fold kvm_mips_comparecount_func() into kvm_mips_comparecount_wakeup() to
eliminate the nondescript function name as well as its unnecessary cast
of a vcpu to "unsigned long" and back to a vcpu.  Presumably func() was
used as a callback at some point during pre-upstream development, as
wakeup() is the only user of func() and has been the only user since
both with introduced by commit 669e846e ("KVM/MIPS32: MIPS arch
specific APIs for KVM").

Cc: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>