kvm: Rename kvm_irqchip_set_irq() to kvm_set_irq()

Rename the function kvm_irqchip_set_irq() to kvm_set_irq(),
since it can be used for sending (asynchronous) interrupts whether
there is a full irqchip model in the kernel or not. (We don't
include 'async' in the function name since asynchronous is the
normal case.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Avi Kivity <avi@redhat.com>