Change default baud rate back to 74906bps, compatible with boot ROM rate

This reverts a behaviour change from 3ceadfc0a6.

examples/simple/simple.c

@@ -1,6 +1,7 @@
 /* Very basic example that just demonstrates we can run at all!
  */
 #include "espressif/esp_common.h"
+#include "esp/uart.h"
 #include "FreeRTOS.h"
 #include "task.h"
 #include "queue.h"
@@ -35,6 +36,7 @@ static xQueueHandle mainqueue;
 
 void user_init(void)
 {
+    uart_set_baud(0, 115200);
     printf("SDK version:%s\n", sdk_system_get_sdk_version());
     mainqueue = xQueueCreate(10, sizeof(uint32_t));
     xTaskCreate(task1, (signed char *)"tsk1", 256, &mainqueue, 2, NULL);