kconfig: Move REGEX to Kconfig

Having this as a Kconfig allows it to be a dependent feature.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/canyonlands_defconfig b/configs/canyonlands_defconfig
index 44d4fbd..e936d7b 100644
--- a/configs/canyonlands_defconfig
+++ b/configs/canyonlands_defconfig
@@ -5,3 +5,4 @@
 CONFIG_DEFAULT_DEVICE_TREE="canyonlands"
 CONFIG_OF_CONTROL=y
 CONFIG_OF_EMBED=y
+CONFIG_REGEX=y