staging: comedi: Replace "is is" with "is"

This patch replace "is is " with "is". The replacement couldn't be
automated because sometimes the first "is" was meant to be another
word.

Signed-off-by: simran singhal <singhalsimran0@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_usb6501.c

@@ -45,7 +45,7 @@
  *	byte 3 is the total packet length
  *
  *	byte 4 is always 00
- *	byte 5 is is the total packet length - 4
+ *	byte 5 is the total packet length - 4
  *	byte 6 is always 01
  *	byte 7 is the command
  *