OMAP3 EVM: remove out-of-bounds array access of gpio_leds

Otherwise we can get the following warning on some compilers:

arch/arm/mach-omap2/board-omap3evm.c:384:11:
warning: array subscript is above array bounds

The omap3evm BSP enables a GPIO LED on the twl4030 chip.  However,
the static gpio_leds array doesn't have an entry for it.  This is
most likely a copy-and-paste error, because it has been in there
since the first commit of the omap3evm BSP (53c5ec31).

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[tony@atomide.com: updated comments with the warning]
Signed-off-by: Tony Lindgren <tony@atomide.com>