riscv: defconfig: enable ARCH_ULTRARISC

Enable `ARCH_ULTRARISC` in the default RISC-V defconfig.

Signed-off-by: Jia Wang <wangjia@ultrarisc.com>
Link: https://patch.msgid.link/20260515-ultrarisc-pinctrl-v1-9-bf559589ea8a@ultrarisc.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>

Author: WangJia-UR

arch/riscv/configs/defconfig

@@ -33,6 +33,7 @@ CONFIG_SOC_STARFIVE=y
 CONFIG_ARCH_SUNXI=y
 CONFIG_ARCH_TENSTORRENT=y
 CONFIG_ARCH_THEAD=y
+CONFIG_ARCH_ULTRARISC=y
 CONFIG_ARCH_VIRT=y
 CONFIG_ARCH_CANAAN=y
 CONFIG_SMP=y