drm/amd/display: Don't leak dc_stream_state.

drm/amd/display: Don't leak dc_stream_state.

Noticed while playing “Valley”, which was causing some 8MB of leakage per
second. kmemleak listed many entries looking like this:

    unreferenced object 0xffff8802c2951800 (size 1024):
      comm "Xorg", pid 2982, jiffies 4297410155 (age 392.787s)
      hex dump (first 32 bytes):
        00 50 f9 0c 04 88 ff ff 98 08 00 00 00 00 00 00  .P..............
        80 07 00 00 00 00 00 00 58 00 00 00 2c 00 00 00  ........X...,...
      backtrace:
        [<ffffffff810cd4c3>] create_object+0x13c/0x261
        [<ffffffff815abdc2>] kmemleak_alloc+0x20/0x3c
        [<ffffffff810cad1d>] slab_post_alloc_hook+0x42/0x52
        [<ffffffff810cb8e0>] kmem_cache_alloc+0x67/0x76
        [<ffffffff813bbb54>] dc_create_stream_for_sink+0x24/0x1cf
        [<ffffffff81373aaa>] create_stream_for_sink+0x6f/0x295
        [<ffffffff81373dc2>] dm_update_crtcs_state+0xa6/0x268
        [<ffffffff8137401e>] amdgpu_dm_atomic_check+0x9a/0x314
        [<ffffffff812ac3dd>] drm_atomic_check_only+0x17a/0x42d
        [<ffffffff812ac6a3>] drm_atomic_commit+0x13/0x4b
        [<ffffffff812ad1a5>] drm_atomic_connector_commit_dpms+0xcb/0xe8
        [<ffffffff812b1238>] drm_mode_obj_set_property_ioctl+0xe6/0x1e3
        [<ffffffff812b027b>] drm_mode_connector_property_set_ioctl+0x2b/0x2d
        [<ffffffff8129f427>] drm_ioctl_kernel+0x64/0x9d
        [<ffffffff8129f6a2>] drm_ioctl+0x230/0x316
        [<ffffffff812ca4d3>] amdgpu_drm_ioctl+0x4b/0x7d

v2: also handle break statements.

Signed-off-by: Darren Salt <devspam@moreofthesa.me.uk>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>