sunxi: Adapt U-Boot config to board rename

The board was renamed without changing the BUILD_DEVICES in the U-Boot
Makefile, this broken the build.

Fixes: 0830ae3a2fdf ("sunxi: Correct manufacturer name to Sinovoip")
Signed-off-by: Hauke Mehrtens <[email protected]>

package/boot/uboot-sunxi/Makefile

@@ -284,7 +284,7 @@ endef
 define U-Boot/Bananapi_M2_Ultra
   BUILD_SUBTARGET:=cortexa7
   NAME:=Bananapi M2 Ultra
-  BUILD_DEVICES:=lemaker_bananapi-m2-ultra
+  BUILD_DEVICES:=sinovoip_bananapi-m2-ultra
 endef
 
 UBOOT_TARGETS := \