davinci: da830: add support for new silicon revisions

Newer revs of da830 silicon have different 'variant' field of the JTAG
id register.  Current code only supports rev 1.0 silicon.

This patch adds support for rev1.1 and rev2.0 silicon and updates
the 'name' strings to add a '-' between 'omap' & 'l137' to have
consistent naming with da850/omap-l138.

From Mark Grosen <mgrosen@ti.com>:

"There are currently three silicon revisions for OMAPL137. The JTAG IDs
 (DEVIDR register contents) for each silicon revision are shown below:

 0x0B7D F02F for silicon revision 1.0
 0x8B7D F02F for silicon revision 1.1
 0x9B7D F02F for silicon revision 2.0

 Corresponding errata documentation will be available in the next few
 weeks on the ti.com website."

Reported-by: Nick Thompson <Nick.Thompson@gefanuc.com>
Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>