stm32/mboot: Remove the use of timeout in DFU_GETSTATUS.

This is treated more like a "delay before continuing" in the spec and
official tools and does not appear to be really needed.  In particular,
downloading firmware is much slower with non-zero timeouts because the host
must pause by the timeout between sending each DFU_GETSTATUS to poll for
download/erase complete.

ports/stm32/mboot/main.c

@@ -800,28 +800,6 @@ static void dfu_init(void) {
     dfu_context.addr = 0x08000000;
 }
 
-// The DFU_GETSTATUS response before dfu_process_dnload is run should include the needed timeout adjustments
-static size_t get_timeout_ms(void) {
-    if (dfu_context.wBlockNum == 0) {
-        // download control commands
-        if (dfu_context.wLength >= 1 && dfu_context.buf[0] == DFU_CMD_DNLOAD_ERASE) {
-            if (dfu_context.wLength == 1) {
-                // mass erase command
-                // It takes 10-12 seconds to erase a 2MB stm part. Extrapolate a suitable timeout from this.
-                return APPLICATION_FLASH_LENGTH / 170;
-
-            } else if (dfu_context.wLength == 5) {
-                // erase page command
-                return 500;
-            }
-        }
-    } else if (dfu_context.wBlockNum > 1) {
-        // write data to memory command
-        return 500;
-    }
-    return 0;
-}
-
 static int dfu_process_dnload(void) {
     int ret = -1;
     if (dfu_context.wBlockNum == 0) {
@@ -922,11 +900,10 @@ static int dfu_handle_tx(int cmd, int arg, int len, uint8_t *buf, int max_len) {
             default:
                 dfu_context.state = DFU_STATE_BUSY;
         }
-        size_t timeout_ms = get_timeout_ms();
         buf[0] = dfu_context.status;          // bStatus
-        buf[1] = (timeout_ms >> 16) & 0xFF;   // bwPollTimeout (ms)
-        buf[2] = (timeout_ms >> 8) & 0xFF;    // bwPollTimeout (ms)
-        buf[3] = timeout_ms & 0xFF;           // bwPollTimeout (ms)
+        buf[1] = 0;                           // bwPollTimeout_lsb (ms)
+        buf[2] = 0;                           // bwPollTimeout     (ms)
+        buf[3] = 0;                           // bwPollTimeout_msb (ms)
         buf[4] = dfu_context.state;           // bState
         buf[5] = dfu_context.error;           // iString
         // Clear errors now they've been sent