drm/komeda: remove redundant assignment to pointer disable_done

drm/komeda: remove redundant assignment to pointer disable_done

The pointer disable_done is being initialized with a value that
is never read and is being re-assigned a little later on. The
assignment is redundant and hence can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: james qian wang (Arm Technology China) <james.qian.wang@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191004162156.325-1-colin.king@canonical.com