dma_terminate_all maybe called in interrupt context which means
WARN_ON() will be triggered as below when bd memory freed. Allocat
bd memory from dma pool instead.

[   29.161079] WARNING: CPU: 1 PID: 533 at ./include/linux/dma-mapping.h:541 sdma_free_bd+0xa4/0xb4
[   29.169883] Modules linked in:
[   29.172990] CPU: 1 PID: 533 Comm: mpegaudioparse0 Not tainted 4.18.0-rc1-next-20180618-00009-gf79f22c #20
[   29.182597] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[   29.189163] Backtrace:
[   29.191685] [<c010d1e0>] (dump_backtrace) from [<c010d4a0>] (show_stack+0x18/0x1c)
[   29.199306]  r7:00000000 r6:600f0093 r5:00000000 r4:c107db7c
[   29.205029] [<c010d488>] (show_stack) from [<c0a5bba0>] (dump_stack+0xb4/0xe8)
[   29.212312] [<c0a5baec>] (dump_stack) from [<c012703c>] (__warn+0x104/0x130)
[   29.219411]  r9:ec3e817c r8:0000021d r7:00000009 r6:c0d1d440 r5:00000000 r4:00000000
[   29.227204] [<c0126f38>] (__warn) from [<c0127180>] (warn_slowpath_null+0x44/0x50)
[   29.234821]  r8:ed129dc4 r7:c0b01978 r6:c04d4e90 r5:0000021d r4:c0d1d440
[   29.241574] [<c012713c>] (warn_slowpath_null) from [<c04d4e90>] (sdma_free_bd+0xa4/0xb4)
[   29.249706]  r6:4c001000 r5:f082e000 r4:00000024
[   29.254376] [<c04d4dec>] (sdma_free_bd) from [<c04d4eb4>] (sdma_desc_free+0x14/0x20)
[   29.262163]  r7:ec3e8110 r6:00000100 r5:00000200 r4:ecf89a00
[   29.267873] [<c04d4ea0>] (sdma_desc_free) from [<c04d229c>] (vchan_dma_desc_free_list+0xa4/0xac)
[   29.276697]  r5:00000200 r4:ed129d9c
[   29.280326] [<c04d21f8>] (vchan_dma_desc_free_list) from [<c04d482c>] (sdma_disable_channel_with_delay+0x14c/0x188)
[   29.290808]  r9:ecae560c r8:ec3e815c r7:00000000 r6:c1008908 r5:ed129dc4 r4:ec3e8110
[   29.298605] [<c04d46e0>] (sdma_disable_channel_with_delay) from [<c07c5c84>] (snd_dmaengine_pcm_trigger+0x90/0x1b0)
[   29.309087]  r8:ecae5000 r7:ec940800 r6:ed31bd80 r5:ecadb200 r4:ec26a700
[   29.315855] [<c07c5bf4>] (snd_dmaengine_pcm_trigger) from [<c07dd800>] (soc_pcm_trigger+0xb4/0x130)
[   29.324953]  r8:ecae5000 r7:ec940800 r6:00000000 r5:ecadb200 r4:ec26a700
[   29.331716] [<c07dd74c>] (soc_pcm_trigger) from [<c07bc008>] (snd_pcm_do_stop+0x58/0x5c)
[   29.339859]  r9:ecaed5a8 r8:ed31bdc0 r7:00000000 r6:00000001 r5:ecadb200 r4:c0b9c4d0
[   29.347652] [<c07bbfb0>] (snd_pcm_do_stop) from [<c07bbde8>] (snd_pcm_action_single+0x40/0x80)
[   29.356315] [<c07bbda8>] (snd_pcm_action_single) from [<c07bbf1c>] (snd_pcm_action+0xf4/0xfc)
[   29.364883]  r7:00000001 r6:c0b9c4d0 r5:ecadb2d4 r4:ecadb200
[   29.370593] [<c07bbe28>] (snd_pcm_action) from [<c07bc8dc>] (snd_pcm_drop+0x58/0x9c)
Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Tested-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Vinod Koul <vkoul@kernel.org>