irqchip/alpine-msi: Don't use <asm-generic/msi.h>

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: marc.zyngier@arm.com
Cc: antoine.tenart@free-electrons.com
Cc: jason@lakedaemon.net
Cc: tsahee@annapurnalabs.com
Link: http://lkml.kernel.org/r/1462459265-20974-1-git-send-email-hch@lst.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>