riscv: Add EFI application infrastructure

The hello world binary and a few selftests require to build EFI target
binaries, not just the EFI host environment.

This patch adds all required files to generate an EFI binary for
RISC-V.

Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
index 2eafd71..cc562f9 100644
--- a/arch/riscv/lib/Makefile
+++ b/arch/riscv/lib/Makefile
@@ -11,3 +11,14 @@
 obj-y	+= cache.o
 obj-y	+= interrupts.o
 obj-y   += setjmp.o
+
+# For building EFI apps
+CFLAGS_$(EFI_CRT0) := $(CFLAGS_EFI)
+CFLAGS_REMOVE_$(EFI_CRT0) := $(CFLAGS_NON_EFI)
+
+CFLAGS_$(EFI_RELOC) := $(CFLAGS_EFI)
+CFLAGS_REMOVE_$(EFI_RELOC) := $(CFLAGS_NON_EFI)
+
+extra-$(CONFIG_CMD_BOOTEFI_HELLO_COMPILE) += $(EFI_CRT0) $(EFI_RELOC)
+extra-$(CONFIG_CMD_BOOTEFI_SELFTEST) += $(EFI_CRT0) $(EFI_RELOC)
+extra-$(CONFIG_EFI) += $(EFI_CRT0) $(EFI_RELOC)