mei: rename enum mei_cb_major_types to enum mei_cb_file_ops

1. Rename mei_cb_major_types to more understandable mei_cb_file_ops
2. Rename member struct mei_cl_cb of this type to simple 'fop_type'
3. Add kernel doc for the type

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/misc/mei/amthif.c b/drivers/misc/mei/amthif.c
index 74d593f..34d37a9 100644
--- a/drivers/misc/mei/amthif.c
+++ b/drivers/misc/mei/amthif.c
@@ -347,7 +347,7 @@
 	if (ret)
 		return ret;
 
-	cb->major_file_operations = MEI_IOCTL;
+	cb->fop_type = MEI_FOP_IOCTL;
 
 	if (!list_empty(&dev->amthif_cmd_list.list) ||
 	    dev->iamthif_state != MEI_IAMTHIF_IDLE) {