uboot-mediatek: update to v2023.04

uboot-mediatek: update to v2023.04

Update to next U-Boot timed release.
Remove now obsolete patch
100-01-board-mediatek-add-more-network-configurations.patch
Default IP addresses are now dealt with in Kconfig, no longer in board-
specific C header files.

Add patches to restore ANSI support in bootmenu which was broken upstream,
always use high-speed mode on serial UART for improved stability and fix
an issue with pinconf not being applied on MT7623 resulting in eMMC
being inaccessible when booting from micro SD card.

In order to keep the size of the bootloader on MT7623 below 512kB remove
some unneeded commands on both MT7623 boards.

Tested on:
 * BananaPi BPi-R2 (MT7623N)
 * BananaPi BPi-R3 (MT7986A)
 * BananaPi BPi-R64 (MT7622A)
 * Linksys E8450 (MT7622B)

Signed-off-by: Daniel Golle <daniel@makrotopia.org>