firmware: imx: Save channel name for further use

We want to request / free channels on demand later in order
to save power.

For this for each channel we save the name and use it to
reference the channel later.

Signed-off-by: Daniel Baluta <[e-mail]>
Reviewed-by: Paul Olaru <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

drivers/firmware/imx/imx-dsp.c

···
 			return -ENOMEM;
 
 		dsp_chan = &dsp_ipc->chans[i];
+		dsp_chan->name = chan_name;
 		cl = &dsp_chan->cl;
 		cl->dev = dev;
 		cl->tx_block = false;
···
 		}
 
 		dev_dbg(dev, "request mbox chan %s\n", chan_name);
-		/* chan_name is not used anymore by framework */
-		kfree(chan_name);
 	}
 
 	return 0;
 out:
-	kfree(chan_name);
 	for (j = 0; j < i; j++) {
 		dsp_chan = &dsp_ipc->chans[j];
 		mbox_free_channel(dsp_chan->ch);
+		kfree(dsp_chan->name);
 	}
 
 	return ret;
···
 	for (i = 0; i < DSP_MU_CHAN_NUM; i++) {
 		dsp_chan = &dsp_ipc->chans[i];
 		mbox_free_channel(dsp_chan->ch);
+		kfree(dsp_chan->name);
 	}
 
 	return 0;