alps64: Fix for delay time for matrix scan

Delay less than 20us can cause false key detection in some situations.
With week internal pull-up takes time to charge stray capacitance of
trace between ground fill(and fingers), perhaps?

In particular, when testing Alps64 PCB without diodes tweezer is used
to close a key and this makes trace longer, more capacitance in result.

keyboard/alps64/matrix.c

@@ -72,7 +72,7 @@ uint8_t matrix_scan(void)
 {
     for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
         select_row(i);
-        _delay_us(1);  // delay for settling
+        _delay_us(30);  // delay for settling
         matrix_row_t cols = read_cols();
         if (matrix_debouncing[i] != cols) {
             if (debouncing) {