OMAP2: Devkit8000: Remove non existing vsim supply

The Devkit8000 uses the cost reduced variant tps65930 of the twl4030.
The TPS65930 only has vdd1, vdd2, vpll1, vio, vmmc1, vdac and vaux2.

vaux2 is not used on Devkit8000.

Signed-off-by: Thomas Weber <weber@corscience.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>