RISC-V: Select GENERIC_UCMPDI2 on RV32I

On 32-bit, it need to use __ucmpdi2, otherwise, it can't find the __ucmpdi2
symbol.
Signed-off-by: NZong Li <zong@andestech.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NPalmer Dabbelt <palmer@sifive.com>

arch/riscv/Kconfig

@@ -107,6 +107,7 @@ config ARCH_RV32I
 	select GENERIC_LIB_ASHLDI3
 	select GENERIC_LIB_ASHRDI3
 	select GENERIC_LIB_LSHRDI3
+	select GENERIC_LIB_UCMPDI2
 
 config ARCH_RV64I
 	bool "RV64I"