Some NanoPC-T6 boards with A3A444 eMMC chips experience I/O errors and
corruption when using HS400 mode. Downgrade to HS200 mode to ensure
stable operation.
Fixes: #18844
Signed-off-by: Grzegorz Sterniczuk <grzegorz@sternicz.uk>
Link: https://github.com/openwrt/openwrt/pull/19398
[Add patch header]
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
