riscv: Fix guest/init linkage for multilib toolchain

For RISC-V multilib toolchains, we must specify -mabi and -march
options when linking guest/init.

Fixes: 2e99678314c2 ("riscv: Initial skeletal support")
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20231118132847.758785-7-apatel@ventanamicro.com
Signed-off-by: Will Deacon <will@kernel.org>
diff --git a/Makefile b/Makefile
index acd5ffd..d84dc8e 100644
--- a/Makefile
+++ b/Makefile
@@ -223,9 +223,11 @@
 	OBJS		+= riscv/aia.o
 	ifeq ($(RISCV_XLEN),32)
 		CFLAGS	+= -mabi=ilp32d -march=rv32gc
+		GUEST_INIT_FLAGS += -mabi=ilp32d -march=rv32gc
 	endif
 	ifeq ($(RISCV_XLEN),64)
 		CFLAGS	+= -mabi=lp64d -march=rv64gc
+		GUEST_INIT_FLAGS += -mabi=lp64d -march=rv64gc
 	endif
 
 	ARCH_WANT_LIBFDT := y