riscv: Add setjmp/longjmp code

To support efi_loader we need to have platform support for setjmp/longjmp.
Add it here.

Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
index 0b671f7..2eafd71 100644
--- a/arch/riscv/lib/Makefile
+++ b/arch/riscv/lib/Makefile
@@ -10,3 +10,4 @@
 obj-$(CONFIG_CMD_GO) += boot.o
 obj-y	+= cache.o
 obj-y	+= interrupts.o
+obj-y   += setjmp.o