genirq: Introduce callback irq_chip.irq_write_msi_msg

Introduce callback irq_chip.irq_write_msi_msg, so we can share common
code among MSI alike interrupt controllers, such as HPET and DMAR.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --cc include/linux/irq.h
Simple merge