irqchip/sirfsoc: Fix sparse warnings on __iomem

irqchip/sirfsoc: Fix sparse warnings on __iomem

Fix warnings from sparse about casting to __iomem from non anotated
variable:

drivers/irqchip/irq-sirfsoc.c:56:47: warning: incorrect type in initializer (different address spaces)
drivers/irqchip/irq-sirfsoc.c:56:47:    expected void [noderef] <asn:2>*base
drivers/irqchip/irq-sirfsoc.c:56:47:    got void *host_data
drivers/irqchip/irq-sirfsoc.c:97:47: warning: incorrect type in initializer (different address spaces)
drivers/irqchip/irq-sirfsoc.c:97:47:    expected void [noderef] <asn:2>*base
drivers/irqchip/irq-sirfsoc.c:97:47:    got void *host_data
drivers/irqchip/irq-sirfsoc.c:109:47: warning: incorrect type in initializer (different address spaces)
drivers/irqchip/irq-sirfsoc.c:109:47:    expected void [noderef] <asn:2>*base
drivers/irqchip/irq-sirfsoc.c:109:47:    got void *host_data

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Link: https://lkml.kernel.org/r/1465301910-2308-1-git-send-email-ben.dooks@codethink.co.uk
Signed-off-by: Jason Cooper <jason@lakedaemon.net>