Allow CONFIG_REGEX to be disabled when CONFIG_NET

Instead of selecting REGEX when NET is enabled, make it the default, but
allow boards that are tiny to disable it and lose functionality on all
but the first Ethernet adapter.

cm-bf548, bf538f-ezkit, and bf533-stamp need this. None appear to have
more than one Ethernet interface.

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

include/env_callback.h

@@ -33,8 +33,10 @@
 
 #ifdef CONFIG_REGEX
 #define ENV_DOT_ESCAPE "\\"
+#define ETHADDR_WILDCARD "\\d?"
 #else
 #define ENV_DOT_ESCAPE
+#define ETHADDR_WILDCARD
 #endif
 
 #ifdef CONFIG_CMD_DNS
@@ -53,7 +55,7 @@
 	"nvlan:nvlan," \
 	"vlan:vlan," \
 	DNS_CALLBACK \
-	"eth\\d?addr:ethaddr,"
+	"eth" ETHADDR_WILDCARD "addr:ethaddr,"
 #else
 #define NET_CALLBACKS
 #endif

lib/Kconfig

@@ -38,6 +38,7 @@ config SYS_VSNPRINTF
 
 config REGEX
 	bool "Enable regular expression support"
+	default y if NET
 	help
 	  If this variable is defined, U-Boot is linked against the
 	  SLRE (Super Light Regular Expression) library, which adds

net/Kconfig

@@ -4,7 +4,6 @@
 
 menuconfig NET
 	bool "Networking support"
-	select REGEX
 
 if NET