dma-trace.c: lower log level of dropped logs

Dropping logs is bad but it should not be fatal in itself.

This ERROR is one of the last remaining one, see
thesofproject/sof-test#1075 (comment)

Signed-off-by: Marc Herbert <[email protected]>

src/trace/dma-trace.c

@@ -650,8 +650,8 @@ static void dtrace_add_event(const char *e, uint32_t length)
 			 * so after it we have to recalculate margin and
 			 * overflow
 			 */
-			tr_err(&dt_tr, "dtrace_add_event(): number of dropped logs = %u",
-			       tmp_dropped_entries);
+			tr_warn(&dt_tr, "dtrace_add_event(): number of dropped logs = %u",
+				tmp_dropped_entries);
 			margin = dtrace_calc_buf_margin(buffer);
 			overflow = dtrace_calc_buf_overflow(buffer, length);
 		}