ARM: OMAP2+: remove custom abort handler for t410

This is not needed anymore. Handling a potentially pending imprecise external
abort left behind by the bootloader is now done in a slightly safer way inside
the common ARM startup code.

With the recent changes to abort handling, this issue got fixed by 57df5380
("ARM: OMAP2+: Fix imprecise external abort caused by bogus SRAM init").

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
[tony@atomide.com: updated comments to describe what fixed the issue]
Signed-off-by: Tony Lindgren <tony@atomide.com>