staging: comedi: ni_660x: checkpatch.pl cleanup (missing blank line)

Fix the checkpatch.pl warning:

WARNING: Missing a blank line after declarations
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_660x.c

@@ -161,6 +161,7 @@ enum ni_660x_register {
 static inline unsigned IOConfigReg(unsigned pfi_channel)
 {
 	unsigned reg = NI660X_IO_CFG_0_1 + pfi_channel / 2;
+
 	BUG_ON(reg > NI660X_IO_CFG_38_39);
 	return reg;
 }