OMAP: ID: introduce chip detection for OMAP4460

Add support for detecting the latest in the OMAP4 family: OMAP4460
Among other changes, the new chip also can support 1.5GHz A9s,
1080p stereoscopic 3D and 12 MP stereo (dual camera). In addition,
we have changes to OPPs supported, clock tree etc, hence having a
chip detection is required.

For more details on OMAP4460, see Highlights:
http://focus.ti.com/general/docs/wtbu/wtbuproductcontent.tsp?contentId=53243&navigationId=12843&templateId=6123

Public TRM is available here as usual:
http://focus.ti.com/general/docs/wtbu/wtbudocumentcenter.tsp?templateId=6123&navigationId=12667



[nm@ti.com: cleanups and introduction of ramp system]
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Aneesh V <aneesh@ti.com>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Reviewed-by: Paul Walmsley <paul@pwsan.com>
[tony@atomide.com: updated to not use CHIP_IS_OMAP44XX]
Signed-off-by: Tony Lindgren <tony@atomide.com>