Add 10ms delay at start of double detector for boards with EZ6301QI to settle

Without this change the board would stay in boot loader when USB cable
is freshly plugged in.

Author: sandeepmistry

bootloaders/zero/board_definitions_arduino_mkrvidor4000.h

@@ -68,6 +68,8 @@
 #define PMIC_PIN_SDA                      11
 #define PMIC_SERCOM                       SERCOM0
 
+#define HAS_EZ6301QI                      1
+
 #define ENABLE_JTAG_LOAD                  1
 #define TDI                               12
 #define TDO                               15

bootloaders/zero/main.c

@@ -106,6 +106,16 @@ static void check_start_application(void)
       return;
     }
 
+#ifdef HAS_EZ6301QI
+    // wait a tiny bit for the EZ6301QI to settle,
+    // as it's connected to RESETN and might reset
+    // the chip when the cable is plugged in fresh
+
+    for (uint32_t i=0; i<2500; i++) /* 10ms */
+      /* force compiler to not optimize this... */
+      __asm__ __volatile__("");
+#endif
+
     /* First tap */
     BOOT_DOUBLE_TAP_DATA = DOUBLE_TAP_MAGIC;