uboot-sunxi: bump to 2023.04

Compile-tested: all boards
Runtime-tested:
 - Cortex-A8: pcDuino
 - Cortex-A7: Bananapro, Bananapi M3
 - Cortex-A53:Pine64+

Notes:
 - binman tries to add firmware for the SCP (system control processor), which
   we don't build, and is optional for the boot process on 64-bit. Disable this
   via setting the SCP envvar to /dev/null. For further info, see [1] .

[1] https://github.com/u-boot/u-boot/blob/master/board/sunxi/README.sunxi64

Signed-off-by: Zoltan HERPAI <wigyori@uid0.hu>