dmatest: prevent memory leakage on error path in thread

When we fail to allocate memory for thread->srcs or thread->dsts and src_cnt or
dst_cnt great than 1 we leak memory on error path. This patch fixes the issue.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index e27cec2..a8d7809 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -688,14 +688,14 @@
 	runtime = ktime_us_delta(ktime_get(), ktime);
 
 	ret = 0;
+err_dstbuf:
 	for (i = 0; thread->dsts[i]; i++)
 		kfree(thread->dsts[i]);
-err_dstbuf:
 	kfree(thread->dsts);
 err_dsts:
+err_srcbuf:
 	for (i = 0; thread->srcs[i]; i++)
 		kfree(thread->srcs[i]);
-err_srcbuf:
 	kfree(thread->srcs);
 err_srcs:
 	kfree(pq_coefs);