Update uboot-at91 to linux4sam-2022.04. As linux4sam-2022.04 is based on
U-Boot v2022.01 which contains commit
93b196532254 ("Makefile: Only build dtc if needed") removed also the DTC
variable passed to MAKE to force the compilation of DTC.
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
(cherry picked from commit 6d5611af28)