ASoC: qcom: q6apm-lpass-dais: Fix NULL pointer dereference if source graph failed

In the Linux kernel, the following vulnerability has been resolved: ASoC: qcom: q6apm-lpass-dais: Fix NULL pointer dereference if source graph failed If earlier opening of source graph fails (e.g. ADSP rejects due to incorrect audioreach topology), the graph is closed and "dai_data->graph[dai->id]" is assigned NULL. Preparing the DAI for sink graph continues though and next call to q6apm_lpass_dai_prepare() receives dai_data->graph[dai->id]=NULL leading to NULL pointer exception: qcom-apm gprsvc:service:2:1: Error (1) Processing 0x01001002 cmd qcom-apm gprsvc:service:2:1: DSP returned error[1001002] 1 q6apm-lpass-dais 30000000.remoteproc:glink-edge:gpr:service@1:bedais: fail to start APM port 78 q6apm-lpass-dais 30000000.remoteproc:glink-edge:gpr:service@1:bedais: ASoC: error at snd_soc_pcm_dai_prepare on TX_CODEC_DMA_TX_3: -22 Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a8 ... Call trace: q6apm_graph_media_format_pcm+0x48/0x120 (P) q6apm_lpass_dai_prepare+0x110/0x1b4 snd_soc_pcm_dai_prepare+0x74/0x108 __soc_pcm_prepare+0x44/0x160 dpcm_be_dai_prepare+0x124/0x1c0