[gd32][build] allow gd32vw553h clean without packages

Co-authored-by: BernardXiong <1241087+BernardXiong@users.noreply.github.com>

Author: Copilot

bsp/gd32/risc-v/gd32vw553h-eval/SConstruct

@@ -17,6 +17,9 @@ except:
     exit(-1)
 
 def bsp_pkg_check():
+    if GetOption('clean'):
+        return
+
     need_update = not packages_available(os.path.abspath('.'), ['gd32-riscv-series-latest'])
 
     if need_update: