firewire: cdev: add_descriptor documentation fix

struct fw_cdev_add_descriptor.length is in quadlets, not in bytes.
Also remove any doubts about the endianess of descriptor data.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

include/linux/firewire-cdev.h

@@ -380,7 +380,7 @@ struct fw_cdev_initiate_bus_reset {
  * @immediate:	If non-zero, immediate key to insert before pointer
  * @key:	Upper 8 bits of root directory pointer
  * @data:	Userspace pointer to contents of descriptor block
- * @length:	Length of descriptor block data, in bytes
+ * @length:	Length of descriptor block data, in quadlets
  * @handle:	Handle to the descriptor, written by the kernel
  *
  * Add a descriptor block and optionally a preceding immediate key to the local
@@ -394,6 +394,8 @@ struct fw_cdev_initiate_bus_reset {
  * If not 0, the @immediate field specifies an immediate key which will be
  * inserted before the root directory pointer.
  *
+ * @immediate, @key, and @data array elements are CPU-endian quadlets.
+ *
  * If successful, the kernel adds the descriptor and writes back a handle to the
  * kernel-side object to be used for later removal of the descriptor block and
  * immediate key.