添加rtthread相关代码

riscv/rtthread/components/fal/SConscript

@@ -0,0 +1,13 @@
+
+from building import *
+
+cwd     = GetCurrentDir()
+src     = Glob('src/*.c')
+CPPPATH = [cwd + '/inc']
+
+if GetDepend(['FAL_USING_SFUD_PORT']):
+    src += Glob('samples/porting/fal_flash_sfud_port.c')
+
+group = DefineGroup('Fal', src, depend = ['RT_USING_FAL'], CPPPATH = CPPPATH)
+
+Return('group')