drm/rockchip: cdn-dp: modify switchdev name to "cdn-dp"

drm/rockchip: cdn-dp: modify switchdev name to "cdn-dp"

If DP and HDMI are enabled at the same board, they will be
register switchdev with the same name in the same directory.
This would cause register switchdev fail.

Resulting in the following error:
[    0.882415] [<ffffff8008212044>] sysfs_warn_dup+0x60/0x7c
[    0.882424] [<ffffff800821212c>] sysfs_create_dir_ns+0x74/0x94
[    0.882436] [<ffffff8008359fc0>] kobject_add_internal+0xc8/0x290
[    0.882446] [<ffffff800835a428>] kobject_add+0xe0/0x10c
[    0.882454] [<ffffff80084c2874>] device_add+0xec/0x508
[    0.882462] [<ffffff80084c2e3c>] device_create_groups_vargs+0xb4/0xf8
[    0.882471] [<ffffff80084c2eac>] device_create_vargs+0x2c/0x34
[    0.882479] [<ffffff80084c2f14>] device_create+0x60/0x80
[    0.882491] [<ffffff80087248bc>] switch_dev_register+0x8c/0x120
[    0.882502] [<ffffff80084709ec>] cdn_dp_bind+0x4c4/0x644
[    0.882511] [<ffffff80084c091c>] component_bind_all+0x94/0x1c0
[    0.882523] [<ffffff8008478550>] rockchip_drm_bind+0x1c4/0xb54
[    0.882533] [<ffffff80084c0554>] try_to_bring_up_master.part.3+0xac/0x114
[    0.882542] [<ffffff80084c0780>] component_add+0x88/0xf8
[    0.882550] [<ffffff8008470504>] cdn_dp_probe+0x140/0x164
[    0.882559] [<ffffff80084c71f8>] platform_drv_probe+0x58/0xa4
[    0.882568] [<ffffff80084c5498>] driver_probe_device+0x118/0x2ac
[    0.882576] [<ffffff80084c5778>] __device_attach_driver+0x88/0x98
[    0.882584] [<ffffff80084c38a0>] bus_for_each_drv+0x7c/0xac
[    0.882592] [<ffffff80084c52cc>] __device_attach+0xa4/0x124
[    0.882600] [<ffffff80084c58e4>] device_initial_probe+0x10/0x18
[    0.882609] [<ffffff80084c4924>] bus_probe_device+0x2c/0x8c
[    0.882617] [<ffffff80084c4da0>] deferred_probe_work_func+0x74/0xa0
[    0.882628] [<ffffff80080b2b38>] process_one_work+0x218/0x3e0
[    0.882636] [<ffffff80080b3538>] worker_thread+0x2e8/0x404
[    0.882644] [<ffffff80080b7e70>] kthread+0xe8/0xf0
[    0.882653] [<ffffff8008082690>] ret_from_fork+0x10/0x40
[    0.882675] kobject_add_internal failed for hdmi with -EEXIST, don't try to
register things with the same name in the same directory.

Change-Id: I0c1b175a2483d5524d9cc0e5261d332c5ad286c8
Signed-off-by: Bin Yang <yangbin@rock-chips.com>