ARM: BCM5301X: remove workaround imprecise abort fault handler

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.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Tested-by: Tyler Baker <tyler.baker@linaro.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>