mimxrt: Improve ticks and sleep functions using GPT.

SysTick cannot wake the CPU from WFI/WFE so a hardware timer is needed to
keep track of ticks/delay (similar to the nrf port).

Fixes issue #7234.

Signed-off-by: Damien George <damien@micropython.org>

ports/mimxrt/main.c

@@ -32,6 +32,7 @@
 #include "py/stackctrl.h"
 #include "lib/utils/gchelper.h"
 #include "lib/utils/pyexec.h"
+#include "ticks.h"
 #include "tusb.h"
 #include "led.h"
 
@@ -41,6 +42,7 @@ void board_init(void);
 
 int main(void) {
     board_init();
+    ticks_init();
     tusb_init();
     led_init();