irqchip/ts4800: Make ts4800_ic_ops static const

ts4800_ic_ops is only referenced in this driver, so make it static.
In additional, it's never get modified thus also make it const.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
Link: https://lkml.kernel.org/r/1455457804.13175.1.camel@ingics.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>