drm/amd/display: Use _free(kfree) for dm_gpureset_commit_state()

Using a _free(kfree) macro drops the need for a goto statement
as it will be freed when it goes out of scope.

Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>