simplify board API, adding stm32f3 discovery

- remove board header since it is not used

examples/device/cdc_msc_hid/ses/lpc18xx/lpc18xx.emProject

@@ -18,7 +18,7 @@
       arm_target_device_name="LPC1857"
       arm_target_interface_type="SWD"
       build_treat_warnings_as_errors="Yes"
-      c_preprocessor_definitions="LPC18xx;__LPC1800_FAMILY;__LPC185x_SUBFAMILY;ARM_MATH_CM3;FLASH_PLACEMENT=1;CORE_M3;BOARD_MCB1800;CFG_TUSB_MCU=OPT_MCU_LPC18XX;CFG_TUSB_MEM_SECTION= __attribute__((section(".bss2")))"
+      c_preprocessor_definitions="LPC18xx;__LPC1800_FAMILY;__LPC185x_SUBFAMILY;ARM_MATH_CM3;FLASH_PLACEMENT=1;CORE_M3;CFG_TUSB_MCU=OPT_MCU_LPC18XX;CFG_TUSB_MEM_SECTION= __attribute__((section(".bss2")))"
       c_user_include_directories="../../src;$(rootDir)/hw;$(rootDir)/hw/mcu/nxp/lpcopen/lpc_chip_18xx/inc;$(rootDir)/hw/mcu/nxp/lpcopen/lpc_chip_18xx/inc/config_18xx;$(rootDir)/src"
       debug_register_definition_file="$(ProjectDir)/LPC18xx_Registers.xml"
       debug_target_connection="J-Link"
@@ -122,6 +122,9 @@
       filter="*.c;*.h"
       path="../../../../../src"
       recurse="Yes" />
+    <configuration
+      Name="MCB1800"
+      c_preprocessor_definitions="BOARD_MCB1800" />
   </project>
   <configuration
     Name="MCB1800"