esp8266: Switch to standard mp_hal_delay_us() MPHAL function.
diff --git a/esp8266/main.c b/esp8266/main.c
index 95315da..18fd2bd 100644
--- a/esp8266/main.c
+++ b/esp8266/main.c
@@ -56,7 +56,7 @@
 
 void soft_reset(void) {
     mp_hal_stdout_tx_str("PYB: soft reset\r\n");
-    mp_hal_udelay(10000); // allow UART to flush output
+    mp_hal_delay_us(10000); // allow UART to flush output
     mp_reset();
     pyexec_event_repl_init();
 }