shorter names for kernel and buildroot dirs

build

@@ -110,7 +110,7 @@ def main(args, extra_args=None):
                 'BR2_TARGET_ROOTFS_INITRAMFS=n',
             ])
         buildroot_config_fragments = [
-            os.path.join(common.root_dir, 'buildroot_config_fragments', 'default')
+            os.path.join(common.root_dir, 'buildroot_config', 'default')
         ] + args.buildroot_config_fragment
 
         # Decide kernel configuration.
@@ -145,7 +145,7 @@ def main(args, extra_args=None):
                     raise Exception('Kernel config fragment file does not exist: {}'.format(args.kernel_custom_config_file))
                 default_kernel_config_fragments = []
             else:
-                kernel_config_fragment_dir = os.path.join(common.root_dir, 'kernel_config_fragments')
+                kernel_config_fragment_dir = os.path.join(common.root_dir, 'kernel_config')
                 default_kernel_config_fragments = ['min']
                 if args.linux_reconfigure:
                     # https://stackoverflow.com/questions/49260466/why-when-i-change-br2-linux-kernel-custom-config-file-and-run-make-linux-reconfi