openwrt

Remove "a" character from the first line of patch
  738-v5.14-01-net-dsa-qca8k-fix-an-endian-bug-in-qca8k-get-ethtool.patch

Otherwise `git am` fails to apply this patch which is annoying when
trying to do some development / rebasing.

Signed-off-by: Marek Behún <kabel@kernel.org>