riscv: bootm: Support booting VxWorks

Register the 'bootm' function for booting VxWorks kernel for
RISC-V architecture.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/riscv/lib/bootm.c b/arch/riscv/lib/bootm.c
index 60b32cc..f36b870 100644
--- a/arch/riscv/lib/bootm.c
+++ b/arch/riscv/lib/bootm.c
@@ -86,7 +86,7 @@
 
 	bootstage_mark(BOOTSTAGE_ID_RUN_OS);
 
-	debug("## Transferring control to Linux (at address %08lx) ...\n",
+	debug("## Transferring control to kernel (at address %08lx) ...\n",
 	      (ulong)kernel);
 
 	announce_and_cleanup(fake);
@@ -118,3 +118,9 @@
 	boot_jump_linux(images, flag);
 	return 0;
 }
+
+int do_bootm_vxworks(int flag, int argc, char * const argv[],
+		     bootm_headers_t *images)
+{
+	return do_bootm_linux(flag, argc, argv, images);
+}