kfifo: rename l to len_to_end in setup_sgl()

So that one can make any sense of the name.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20240405060826.2521-6-jirislaby@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>