riscv: Enable GENERIC_IRQ_SHOW_LEVEL

The interrupt controllers on riscv support both edge and level triggered
interrupts, it's useful to provide that information in /proc/interrupts.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/Kconfig

@@ -52,6 +52,7 @@ config RISCV
 	select GENERIC_IOREMAP
 	select GENERIC_IRQ_MULTI_HANDLER
 	select GENERIC_IRQ_SHOW
+	select GENERIC_IRQ_SHOW_LEVEL
 	select GENERIC_LIB_DEVMEM_IS_ALLOWED
 	select GENERIC_PCI_IOMAP
 	select GENERIC_PTDUMP if MMU