Add validation on attr type and size in a2dp_api.cc

Handling automerger reported conflicts in the following brances:
- b/304684796
= b/304651812
- b/304652020

Bug: 263958603

Test: atest net_test_stack_a2dp_native
Ignore-AOSP-First: security
Tag: #security
Merged-In: I938467ca4f4b130cd8b4c544096127e679391c06
Change-Id: If8edc7c50a200c3ffaf10d500c47aec38058da3c
(cherry picked from commit 4832e302)