staging: most: refactor channel structure

The struct most_c_obj has the same set of attributes for each of two AIMs.
This patch cleans up the code by introducing the new struct most_c_aim_obj
hat contains those fields.

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