riscv: Probe cpus during boot

This calls cpu_probe_all() to probe all available cpus.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
diff --git a/arch/riscv/cpu/qemu/Kconfig b/arch/riscv/cpu/qemu/Kconfig
index 2e953e1..f48751e 100644
--- a/arch/riscv/cpu/qemu/Kconfig
+++ b/arch/riscv/cpu/qemu/Kconfig
@@ -4,6 +4,7 @@
 
 config QEMU_RISCV
 	bool
+	select ARCH_EARLY_INIT_R
 	imply CPU
 	imply CPU_RISCV
 	imply RISCV_TIMER