mtd: Add missing 'mtdinfo'

Commit 9277cb760a4cc6e62d0cd23fa938dd953e875a13 added support
for mtdinfo to mtd.mk but missed corresponding Config.in stuff.

Signed-off-by: Michael Roth <mroth@nessie.de>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/mtd/Config.in

@@ -93,6 +93,10 @@ config BR2_PACKAGE_MTD_SERVE_IMAGE
 config BR2_PACKAGE_MTD_SUMTOOL
 	bool "sumtool"
 
+config BR2_PACKAGE_MTD_MTDINFO
+	bool "mtdinfo"
+	default y
+
 config BR2_PACKAGE_MTD_UBIATTACH
 	bool "ubiattach"
 	default y