Try with search_path for some avb path args

If we can't find relative signing_helper path, try with the OPTIONS.search_path dir prefix, and integrate the avb_*_key_path for the same logic.

Test: Build && releasetools_test

Signed-off-by: zhangyongpeng <zhangyongpeng@xiaomi.com>
Change-Id: Ifb1096ddea90693668f3344eb242bf9725113d11
diff --git a/tools/releasetools/verity_utils.py b/tools/releasetools/verity_utils.py
index 755241d..dddb7f4 100644
--- a/tools/releasetools/verity_utils.py
+++ b/tools/releasetools/verity_utils.py
@@ -141,11 +141,7 @@
     self.footer_type = footer_type
     self.avbtool = avbtool
     self.algorithm = algorithm
-    self.key_path = key_path
-    if key_path and not os.path.exists(key_path) and OPTIONS.search_path:
-      new_key_path = os.path.join(OPTIONS.search_path, key_path)
-      if os.path.exists(new_key_path):
-        self.key_path = new_key_path
+    self.key_path = common.ResolveAVBSigningPathArgs(key_path)
 
     self.salt = salt
     self.signing_args = signing_args