Remove duplicated sources that go into hiddenapi-mappins

framework-srcs are already coming from metalava-api-stubs-default (via
framework-minus-apex). We don't need to give framework-srcs again.

Test: choosecombo into sdk_phone_arm7
Test: m
out/soong/.intermediates/frameworks/base/hiddenapi-mappings/android_common/api-versions.xml
out/soong/.intermediates/frameworks/base/hiddenapi-mappings/android_common/dex-mapping.txt
out/soong/.intermediates/frameworks/base/hiddenapi-mappings/android_common/hiddenapi-mappings-stubs.srcjar
out/soong/.intermediates/frameworks/base/hiddenapi-mappings/android_common/hiddenapi-mappings_annotations.zip
is successful

Exempt-From-Owner-Approval: Approved internally
Merged-In: I9ea6e06e8bd388f3a495acb6ff5555c0ce2f75b2
(cherry picked from commit 68020f8f63)
Change-Id: I9ea6e06e8bd388f3a495acb6ff5555c0ce2f75b2

Android.bp

@@ -1263,7 +1263,7 @@ droidstubs {
 droidstubs {
     name: "hiddenapi-mappings",
     defaults: ["metalava-api-stubs-default"],
-    srcs: framework_srcs + [
+    srcs: [
         ":non_openjdk_java_files",
         ":openjdk_java_files",
         ":opt-telephony-common-srcs",