fix(pycardium): Optimize usage of epic_sleep

pycardium/mphalport.c

@@ -260,7 +260,7 @@ static void systick_delay(uint32_t us)
 			/* Add some error margin to avoid issues with the clock accuracy
 			 * of epicardium. We will account for the actual time via our
 			 * (accurate) systick */
-			epic_sleep(sleep_time / 2);
+			epic_sleep(sleep_time * 8 / 10);
 
 			/* epic_sleep() can return early if there was an interrupt
 			 * coming from epicardium side.