package/dahdi-linux: fix typo in Config.in

Fix typo added with commit d959966b41bd88a36664c733a8a8d2b6809e4fc2

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/dahdi-linux/Config.in

@@ -1,5 +1,5 @@
 config BR2_PACKAGE_DAHDI_LINUX
-	bool "dhadi-linux"
+	bool "dahdi-linux"
 	depends on BR2_LINUX_KERNEL
 	help
 	  DAHDI (Digium/Asterisk Hardware Device Interface) is the open