arm: davinci: Fix low level gpio irq handlers' argument

Commit 74164016

 ("arm: davinci: Fix fallout from generic irq chip
conversion") introduced a bug, causing low level interrupt handlers to
get a bogus irq number as an argument. The gpio irq handler falsely
assumes that the handler data is the irq base number and that is no
longer true.

Set the irq handler data to be a pointer to the corresponding gpio
controller. The chained irq handler can then use it to extract both the
irq base number and the gpio registers structure.

Signed-off-by: Ido Yariv <ido@wizery.com>
CC: Thomas Gleixner <tglx@linutronix.de>
[nsekhar@ti.com: renamed "ctl" to "d", simplified indexing logic for chips and
took care of odd bank handling in irq handler]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>