omap: Add chip id recognition for OMAP4 ES2.1 and ES2.2

Allow OMAP4 ES2.1 and ES2.2 revisions to be recognized in the
omap4_check_revision() function.

Mainly, ES2.1 has fixes that allow LPDDR to be used at 100% OPP (400MHz).
ES2.2 additionally has a couple of power management fixes (to reduce
leakage), an I2C1 SDA line state fix, and a floating point write
corruption fix (cortex erratum).

Even though the current mainline support doesn't need to distinguish
between ES2.X versions, it's still useful to know the correct silicon
rev when issues are reported. Moreover, these id checks can be used by
power management code that selects suitable OPPs considering the
memory speed limitation on ES2.0.

For details about the silicon errata on OMAP4430, refer
http://focus.ti.com/pdfs/wtbu/SWPZ009A_OMAP4430_Errata_Public_vA.pdf



Signed-off-by: Nishant Kamat <nskamat@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>