BTA_GATTC_SRVC_CHG_EVT: use proper field

Follow-up of aosp/3185960 to expand fix to all applicable cases

Bug: 328846967
Test: m com.android.btservices
Flag: EXEMPT, minor bugfix
Change-Id: I9aa02504d7d2123cc7e31af82c09a0c6c51d2e67