ARM: dts: omap4-sdp: Add keypad data

Add keypad data node in omap4 device tree file.
Also fill the device tree binding parameters
with the required value in "omap4-sdp" dts file.

Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Felipe Balbi <balbi@ti.com>
Signed-off-by: Benoit Cousson <b-cousson@ti.com>
[b-cousson@ti.com: Re-align the entries and the comments]