scsi: csiostor: Add missing description for csio_rnode_fwevt_handler()'s 'fwevt' param

Fixes the following W=1 kernel build warning(s):

drivers/scsi/csiostor/csio_rnode.c:869: warning: Function parameter or member 'fwevt' not described in 'csio_rnode_fwevt_handler'

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/csiostor/csio_rnode.c

···
 /**
  * csio_rnode_fwevt_handler - Event handler for firmware rnode events.
  * @rn:		rnode
- *
+ * @fwevt:	firmware event to handle
  */
 void
 csio_rnode_fwevt_handler(struct csio_rnode *rn, uint8_t fwevt)