[bsp][stm32f303-nucleo]remove illegal bsp ci. | 移除不合法bsp的ci.

.travis.yml

@@ -76,7 +76,6 @@ env:
   - RTT_BSP='stm32f429-disco' RTT_TOOL_CHAIN='sourcery-arm' 
   - RTT_BSP='stm32l475-iot-disco' RTT_TOOL_CHAIN='sourcery-arm' 
   - RTT_BSP='stm32l476-nucleo' RTT_TOOL_CHAIN='sourcery-arm' 
-  - RTT_BSP='stm32f303-nucleo' RTT_TOOL_CHAIN='sourcery-arm'
 #  - RTT_BSP='taihu' RTT_TOOL_CHAIN='sourcery-ppc'
 #  - RTT_BSP='upd70f3454' # iar
 #  - RTT_BSP='x86' # x86