Dummy dai can be used by multiple sound card. But it only belong to one
card's dapm list. If another card use it, there will be dapm_assert_locked
warning.

[   20.015782] WARNING: CPU: 1 PID: 661 at sound/soc/soc-dapm.c:124 dapm_assert_locked.isra.36+0x4c/0x58()
[   20.025249] Modules linked in:
[   20.028349] CPU: 1 PID: 661 Comm: aplay Not tainted 4.1.0-rc6-next-20150605-00004-gaee05d8-dirty #92
[   20.037528] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[   20.044110] Backtrace:
[   20.046614] [<80012e00>] (dump_backtrace) from [<80012fa0>] (show_stack+0x18/0x1c)
[   20.054229]  r6:809e8060 r5:00000000 r4:00000000 r3:00000000
[   20.060002] [<80012f88>] (show_stack) from [<807a0f74>] (dump_stack+0x80/0x9c)
[   20.067293] [<807a0ef4>] (dump_stack) from [<8002b144>] (warn_slowpath_common+0x7c/0xb4)
[   20.075427]  r5:0000007c r4:00000000
[   20.079065] [<8002b0c8>] (warn_slowpath_common) from [<8002b1a0>] (warn_slowpath_null+0x24/0x2c)
[   20.087898]  r8:00000001 r7:88007c28 r6:ed94a680 r5:809e83e4 r4:ed83d6c0
[   20.094747] [<8002b17c>] (warn_slowpath_null) from [<8058403c>] (dapm_assert_locked.isra.36+0x4c/0x58)
[   20.104101] [<80583ff0>] (dapm_assert_locked.isra.36) from [<805842ec>] (dapm_mark_dirty+0x64/0xa4)
[   20.113165] [<80584288>] (dapm_mark_dirty) from [<805853a8>] (soc_dapm_dai_stream_event.isra.42+0x30/0xc8)
[   20.122863]  r8:ed9b5dbc r7:00000000 r6:00000001 r5:00000001 r4:ed83d6c0
[   20.129706] [<80585378>] (soc_dapm_dai_stream_event.isra.42) from [<80587e28>] (snd_soc_dapm_stream_event+0x78/0xa0)
[   20.140264]  r5:ee2ee62c r4:00000001
[   20.143918] [<80587db0>] (snd_soc_dapm_stream_event) from [<8058957c>] (soc_pcm_prepare+0x138/0x21c)
[   20.153058]  r8:ed8d9480 r7:00000000 r6:ed9b0e00 r5:00000001 r4:ee2ee62c r3:00000000
...

This patch is to not probe the dummy component in soc_probe_component. Then
there is no widget created for dummy DAI, and also don't need to check the
dummy dai in dapm_connect_dai_link_widgets().
Signed-off-by: Shengjiu Wang <shengjiu.wang@freescale.com>
Signed-off-by: Mark Brown <broonie@kernel.org>