Staging: comedi: addi_common.h: Checkpatch cleanup

ERROR: code indent should use tabs where possible
+        const struct comedi_lrange *pr_AiRangelist;^I/* rangelist for A/D */$

ERROR: code indent should use tabs where possible
+        const struct comedi_lrange *pr_AoRangelist;^I/* rangelist for D/A */$

Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>