staging: greybus: audio: Fix possible leak free widgets in gbaudio_dapm_free_controls

In gbaudio_dapm_free_controls(), if one of the widgets is not found, an error
will be returned directly, which will cause the rest to be unable to be freed,
resulting in leak.

This patch fixes the bug. If if one of them is not found, just skip and free the others.

Fixes: 510e340e ("staging: greybus: audio: Add helper APIs for dynamic audio module")
Reported-by: Hulk Robot <hulkci@huawei.com>
Reviewed-by: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Link: https://lore.kernel.org/r/20201205103827.31244-1-wanghai38@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/audio_helper.c

@@ -135,7 +135,8 @@ int gbaudio_dapm_free_controls(struct snd_soc_dapm_context *dapm,
 		if (!w) {
 			dev_err(dapm->dev, "%s: widget not found\n",
 				widget->name);
-			return -EINVAL;
+			widget++;
+			continue;
 		}
 		widget++;
 #ifdef CONFIG_DEBUG_FS