lib: Kconfig.debug: Typo remove extra "it"

The patch below removes an extra "it" in the comment.
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

lib/Kconfig.debug

@@ -835,7 +835,7 @@ config DEBUG_CREDENTIALS
 
 #
 # Select this config option from the architecture Kconfig, if it
-# it is preferred to always offer frame pointers as a config
+# is preferred to always offer frame pointers as a config
 # option on the architecture (regardless of KERNEL_DEBUG):
 #
 config ARCH_WANT_FRAME_POINTERS