scsi: core: Minor comment fixes for scsi_host_busy()

I guess that the @shost comment on scsi_host_busy() was copied from
scsi_host_get() (as it is the same), however they do not do the same
thing.

Also drop reference to busy counter, which has been removed.

Signed-off-by: John Garry <[e-mail]>
Reviewed-by: Bart Van Assche <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/hosts.c

···
 }
 
 /**
- * scsi_host_busy - Return the host busy counter
- * @shost:	Pointer to Scsi_Host to inc.
+ * scsi_host_busy - Return the count of in-flight commands
+ * @shost:	Pointer to Scsi_Host
  **/
 int scsi_host_busy(struct Scsi_Host *shost)
 {