riscv: config: enable ARCH_CANAAN in defconfig

Since K230 has been supported, allow ARCH_CANAAN to be selected to build dt
and drivers for it in defconfig.

Signed-off-by: Yangyu Chen <cyy@cyyself.name>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>

arch/riscv/configs/defconfig

@@ -33,6 +33,7 @@ CONFIG_SOC_STARFIVE=y
 CONFIG_ARCH_SUNXI=y
 CONFIG_ARCH_THEAD=y
 CONFIG_SOC_VIRT=y
+CONFIG_ARCH_CANAAN=y
 CONFIG_SMP=y
 CONFIG_HOTPLUG_CPU=y
 CONFIG_PM=y