[U-Boot] Proper CONFIG_SPL_TEXT_BASE value for OMAP3

ti_omap3_common.h defines CONFIG_SPL_TEXT_BASE to 0x40200800, however a significant number of omap3 boards un-define this and redefine it to 0x40200000

Is there any reason, we couldn't just make ti_omap3_common.h define CONFIG_SPL_TEXT_BASE to 0x40200000? (or better yet migrate to Kconfig and make 0x40200000 the default)?

Boarding using 0x40200800 (default)

cm_t35.h am3517_crane.h tao3530.h

Board using 0x40200000: omap3_logic.h tricorder.h omap3_evm.h tam3517-common.h omap3_beagle.h omap3_overo.h sniper.h omap3_igep00x0.h devkit8000.h include/configs/am3517_evm.h

If we do that, we can limit the number of undefs and redefines and clean up the headers a bit.

adam