staging: most: cdev: simplify list iteration

This patch uses a less confusing list traversing structure to
either return an item of the list that meets the prerequisites
or NULL otherwise.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Link: https://lore.kernel.org/r/1592815695-19305-7-git-send-email-christian.gromm@microchip.com


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