fix Config.in tab usage

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/util-linux/Config.in b/util-linux/Config.in
index 6999b28..acd74a2 100644
--- a/util-linux/Config.in
+++ b/util-linux/Config.in
@@ -789,9 +789,9 @@
 	  systems.
 
 config RDEV
-       bool "rdev"
-       default n
-       help
+	bool "rdev"
+	default n
+	help
 	  Print the device node associated with the filesystem mounted at '/'.
 
 config READPROFILE