uboot-mediatek: update Airoha EN8811H driver

uboot-mediatek: update Airoha EN8811H driver

Use the version sent to upstream U-Boot[1], which has much better
code quality and also works better (without packet loss).

The `en8811h_read_fw` func is adapted to use current read logic.

1. https://lore.kernel.org/u-boot/20250720122852.22563-1-lucienzx159@gmail.com/

Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>
Link: https://github.com/openwrt/openwrt/pull/20000
(cherry picked from commit b63a48b012b7af0da14ea04ff345512254dc69d6)
Link: https://github.com/openwrt/openwrt/pull/20146
Signed-off-by: Robert Marko <robimarko@gmail.com>