arm-trusted-firmware-mediatek: fix NAND read failure on SNFI

arm-trusted-firmware-mediatek: fix NAND read failure on SNFI

A bug has plagued bl2 which caused failure to boot and bricked Linksys
E8450 and Belkin RT3200 devices in case of correctable bitflips being
detected during a read operation. A simple logic error resulted in read
to be considered errornous instead of just continueing in case of
correctable bitflips.

Address this by importing a patch fixing that logic error.

The issue, which has been dubbed as the "OpenWrt Kiss of Death", and is
now a thing of the past.

Users should preemptively update bl2 to prevent their devices being at
risk.

Link: https://github.com/mtk-openwrt/arm-trusted-firmware/pull/11
Signed-off-by: Daniel Golle <daniel@makrotopia.org>