修正stm32f746-disco和FPU相关的flag错误

bsp/stm32/stm32f746-st-disco/rtconfig.py

@@ -42,7 +42,7 @@ if PLATFORM == 'gcc':
     OBJCPY = PREFIX + 'objcopy'
     STRIP = PREFIX + 'strip'
 
-    DEVICE = ' -mcpu=' + CPU + ' -mthumb -mfpu=fpv5-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections'
+    DEVICE = ' -mcpu=' + CPU + ' -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections'
     CFLAGS = DEVICE + ' -g -Wall'
     AFLAGS = ' -c' + DEVICE + ' -x assembler-with-cpp -Wa,-mimplicit-it=thumb '
     LFLAGS = DEVICE + ' -Wl,--gc-sections,-Map=rtthread.map,-cref,-u,Reset_Handler -T board/linker_scripts/link.lds'