riscv: dts: canaan: build all devicetress if SOC_CANAAN

Testing & checking the Canaan devicetrees is inconvenient as only the
devicetree corresponding to SOC_CANAAN_K210_DTB_BUILTIN will be built.
Change the Makefile so that all devicetrees are built by default if
SOC_CANAAN but only the one specified by SOC_CANAAN_K210_DTB_BUILTIN
gets built as an object.
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220705215213.1802496-14-mail@conchuod.ieSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/boot/dts/canaan/Makefile

 # SPDX-License-Identifier: GPL-2.0
-dtb-$(CONFIG_SOC_CANAAN_K210_DTB_BUILTIN) += $(addsuffix .dtb, $(CONFIG_SOC_CANAAN_K210_DTB_SOURCE))
-obj-$(CONFIG_SOC_CANAAN_K210_DTB_BUILTIN) += $(addsuffix .o, $(dtb-y))
+dtb-$(CONFIG_SOC_CANAAN) += canaan_kd233.dtb
+dtb-$(CONFIG_SOC_CANAAN) += k210_generic.dtb
+dtb-$(CONFIG_SOC_CANAAN) += sipeed_maix_bit.dtb
+dtb-$(CONFIG_SOC_CANAAN) += sipeed_maix_dock.dtb
+dtb-$(CONFIG_SOC_CANAAN) += sipeed_maix_go.dtb
+dtb-$(CONFIG_SOC_CANAAN) += sipeed_maixduino.dtb
+
+obj-$(CONFIG_SOC_CANAAN_K210_DTB_BUILTIN) += $(addsuffix .dtb.o, $(CONFIG_SOC_CANAAN_K210_DTB_SOURCE))