KVM: Use cond_resched() directly and remove useless kvm_resched()

Since the commit 15ad7146 ("KVM: Use the scheduler preemption notifiers
to make kvm preemptible"), the remaining stuff in this function is a
simple cond_resched() call with an extra need_resched() check which was
there to avoid dropping VCPUs unnecessarily.  Now it is meaningless.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
kvm: replace cond_resched() with schedule()

	This commit tries to fix qemu CPU soft-lock while using
	>=2 vCPU per guest with BFS enabled. The trick is stolen
	from here:
	https://bugzilla.redhat.com/show_bug.cgi?id=1038929#c5
Merge branch 'fixes-3.13' into pf-3.13