ARM: sunxi: Fix Mini X-plus device tree build

Commit b00adbe0 ("ARM: sunxi: Rename uart nodes to serial") changed the
node names in the DTSI, changes that were not accordingly made to the
Mini X-Plus device tree. This breakage slipped through because it was
not properly declared in the Makefile.

Fix both issues.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
index b9f7121..f0895c5 100644
--- a/arch/arm/boot/dts/Makefile
+++ b/arch/arm/boot/dts/Makefile
@@ -177,7 +177,9 @@
 	spear320-evb.dtb \
 	spear320-hmi.dtb
 dtb-$(CONFIG_ARCH_SPEAR6XX)+= spear600-evb.dtb
-dtb-$(CONFIG_ARCH_SUNXI) += sun4i-a10-cubieboard.dtb \
+dtb-$(CONFIG_ARCH_SUNXI) += \
+	sun4i-a10-cubieboard.dtb \
+	sun4i-a10-mini-xplus.dtb \
 	sun4i-a10-hackberry.dtb \
 	sun5i-a13-olinuxino.dtb
 dtb-$(CONFIG_ARCH_TEGRA) += tegra20-harmony.dtb \