[SCSI] sg: Only print SCSI data direction warning once for a command

When I use cdparanoia my logs get spammed a lot by

printk: 464 messages suppressed.
sg_write: data in/out 30576/30576 bytes for SCSI command 0xbe--guessing data in;
   program cdparanoia not setting count and/or reply_len properly
printk: 1078 messages suppressed.

and many more of those. With this patch the message is only printed once
for a command in a row.

v1->v2: Prevent rate limit messages too (pointed out by jejb)

Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>