ARM: dts: meson: build the Meson8b .dtbs with MACH_MESON8

Currently there are two identical Kconfig options where only differences
are the Kconfig help text and the list of .dtbs that are built:
- MACH_MESON8
- MACH_MESON8B

Build the Meson8b .dtbs when MACH_MESON8 is selected to get rid of the
latter Kconfig symbol later.
Suggested-by: NKevin Hilman <khilman@baylibre.com>
Signed-off-by: NMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: NKevin Hilman <khilman@baylibre.com>

arch/arm/boot/dts/Makefile

@@ -313,14 +313,13 @@ dtb-$(CONFIG_MACH_MESON6) += \
 	meson6-atv1200.dtb
 dtb-$(CONFIG_MACH_MESON8) += \
 	meson8-minix-neo-x8.dtb \
+	meson8b-mxq.dtb \
+	meson8b-odroidc1.dtb \
 	meson8m2-mxiii-plus.dtb
 dtb-$(CONFIG_ARCH_MMP) += \
 	pxa168-aspenite.dtb \
 	pxa910-dkb.dtb \
 	mmp2-brownstone.dtb
-dtb-$(CONFIG_MACH_MESON8B) += \
-	meson8b-mxq.dtb \
-	meson8b-odroidc1.dtb
 dtb-$(CONFIG_ARCH_MPS2) += \
 	mps2-an385.dtb \
 	mps2-an399.dtb