serial_irq: Support side channel for entering bootloader

Add a mechanism to request the bootloader when using serial input.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/generic/serial_irq.c

@@ -79,6 +79,9 @@ console_task(void)
     if (ret > 0)
         command_dispatch(receive_buf, pop_count);
     if (ret) {
+        if (CONFIG_SERIAL_BOOTLOADER_SIDECHANNEL && ret < 0 && pop_count == 32
+            && !memcmp(receive_buf, " \x1c Request Serial Bootloader!! ~", 32))
+            bootloader_request();
         console_pop_input(pop_count);
         if (ret > 0)
             command_send_ack();