rt-thread: take spi bus

sys/rt-thread/port/u8g2_port.c

@@ -349,6 +349,7 @@ uint8_t u8x8_byte_rtthread_4wire_hw_spi(u8x8_t *u8x8, uint8_t msg, uint8_t arg_i
             break;
 
         case U8X8_MSG_BYTE_START_TRANSFER:
+            rt_spi_take_bus(&u8g2_spi_dev);
             u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_enable_level);  
             u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->post_chip_enable_wait_ns, NULL);
             break;
@@ -356,6 +357,7 @@ uint8_t u8x8_byte_rtthread_4wire_hw_spi(u8x8_t *u8x8, uint8_t msg, uint8_t arg_i
         case U8X8_MSG_BYTE_END_TRANSFER:
             u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->pre_chip_disable_wait_ns, NULL);
             u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);
+            rt_spi_release_bus(&u8g2_spi_dev);
             break;
 
         default: