net: Make CMD_NET a menuconfig

Previously, CMD_NET was an alias for 2 commands (bootp and tftpboot) and
they we not able to be disabled. Separate out those 2 commands and move
CMD_NET up to the menu level, which more accurately represents the code.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

Reviewed-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Duncan Hare <dh@synoia.com>
diff --git a/cmd/net.c b/cmd/net.c
index d7c776a..67888d4 100644
--- a/cmd/net.c
+++ b/cmd/net.c
@@ -14,6 +14,7 @@
 
 static int netboot_common(enum proto_t, cmd_tbl_t *, int, char * const []);
 
+#ifdef CONFIG_CMD_BOOTP
 static int do_bootp(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	return netboot_common(BOOTP, cmdtp, argc, argv);
@@ -24,7 +25,9 @@
 	"boot image via network using BOOTP/TFTP protocol",
 	"[loadAddress] [[hostIPaddr:]bootfilename]"
 );
+#endif
 
+#ifdef CONFIG_CMD_TFTPBOOT
 int do_tftpb(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int ret;
@@ -40,6 +43,7 @@
 	"boot image via network using TFTP protocol",
 	"[loadAddress] [[hostIPaddr:]bootfilename]"
 );
+#endif
 
 #ifdef CONFIG_CMD_TFTPPUT
 static int do_tftpput(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])