env: SKRmini can't use STLink (#15645)

platformio.ini

 lib_ignore    = Adafruit NeoPixel, SPI
 src_filter    = ${common.default_src_filter} +<src/HAL/HAL_STM32F1>
 monitor_speed = 250000
+debug_tool    = stlink
+upload_protocol = stlink
 
 #
 # STM32F103RC_fysetc
 lib_ignore        = Adafruit NeoPixel, SPI
 src_filter        = ${common.default_src_filter} +<src/HAL/HAL_STM32F1>
 monitor_speed     = 115200
-upload_protocol   = stlink
-debug_tool        = stlink
 
 [env:STM32F103RC_bigtree_USB]
 platform          = ststm32
 platform_packages = tool-stm32duino
 extra_scripts     = buildroot/share/PlatformIO/scripts/STM32F103RC_SKR_MINI.py
 build_flags       = !python Marlin/src/HAL/HAL_STM32F1/build_flags.py
-  ${common.build_flags} -DDEBUG_LEVEL=0 -DUSE_USB_COMPOSITE -std=gnu++14
+  ${common.build_flags} -DDEBUG_LEVEL=0 -std=gnu++14 -DUSE_USB_COMPOSITE
 build_unflags     = -std=gnu++11
 lib_deps          = ${common.lib_deps}
 lib_ignore        = Adafruit NeoPixel, SPI
 src_filter        = ${common.default_src_filter} +<src/HAL/HAL_STM32F1>
 monitor_speed     = 115200
-upload_protocol   = stlink
-debug_tool        = stlink
 
 #
 # STM32F4 with STM32GENERIC