staging: most: core: constify structure member

This patch adds the const qualifier to the declaration of the member
name_suffix of structure most_channel_capability. It is needed since it
points to string literals.

Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>