staging: most: aim-cdev: fix reported error codes

Currently, the aim-cdev is returning different error codes for the same
root cause. This patch is needed to get rid of the module's inconsistency
when reporting errors.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>