riscv: add binfmt_flat support

Just use the generic definitions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 0c4b122..2c19baa 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -17,6 +17,7 @@
 	select OF
 	select OF_EARLY_FLATTREE
 	select OF_IRQ
+	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_WANT_FRAME_POINTERS
 	select CLONE_BACKWARDS
 	select COMMON_CLK