ARM: OMAP2: Enable Errata 430973 for OMAP3

Enable Erratum 430973 similar to commit 5c86c533

 ("ARM:
omap2plus_defconfig: Enable ARM erratum 430973 for omap3") - Since
multiple defconfigs can exist from various points of view (multi_v7,
omap2plus etc.. it is always better to enable the erratum from the
Kconfig selection point of view so that downstream kernels dont have
to rediscover this all over again.

Reported-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>