cmd: Make bootvx independent of bootelf

There are lots of usecases for running baremetal ELF
binaries via bootelf but if you enable bootelf you
get bootvx as well and you probably don't want or need
it.

Hide bootvx behind it's own configuration option.

Signed-off-by: Daniel Palmer <daniel@0x0f.com>
diff --git a/cmd/elf.c b/cmd/elf.c
index f07e344..114f2ca 100644
--- a/cmd/elf.c
+++ b/cmd/elf.c
@@ -10,8 +10,10 @@
 #include <env.h>
 #include <image.h>
 #include <log.h>
+#ifdef CONFIG_CMD_ELF_BOOTVX
 #include <net.h>
 #include <vxworks.h>
+#endif
 #ifdef CONFIG_X86
 #include <vesa.h>
 #include <asm/cache.h>
@@ -100,6 +102,7 @@
 	return rcode;
 }
 
+#ifdef CONFIG_CMD_ELF_BOOTVX
 /*
  * Interpreter command to boot VxWorks from a memory image.  The image can
  * be either an ELF image or a raw binary.  Will attempt to setup the
@@ -307,6 +310,7 @@
 
 	return 1;
 }
+#endif
 
 U_BOOT_CMD(
 	bootelf, CONFIG_SYS_MAXARGS, 0, do_bootelf,
@@ -323,8 +327,10 @@
 #endif
 );
 
+#ifdef CONFIG_CMD_ELF_BOOTVX
 U_BOOT_CMD(
 	bootvx, 2, 0, do_bootvx,
 	"Boot vxWorks from an ELF image",
 	" [address] - load address of vxWorks ELF image."
 );
+#endif