davinci: dm646x: Add support for 3.x silicon revision

DM6467 silicon revisions 3.x have variant field in JTAGID register as '1'.
This path adds entry for the same in dm646x_ids to be able to boot on boards
with 3.x revision chips.

Also modifies name for 'variant=0' (revisions 1.0, 1.1).

Signed-off-by: Hemant Pedanekar <hemantp@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>