Bluedroid: Update PBAP Filter logic to avoid loss of fields.

In PBAP there are filters for unsupported fields. But the logic
to check these has issue. It checks for Attribute string holds
unsupported parameter, rather than begins with.  So if the
field data has pattern matching unsupported field, that complete
attribute are being removed. The current logic fixes the issue.

Change-Id: Iafcc2915a81e3847f7bfe435a3329b708980af6e
CRs-Fixed: 509165
(cherry picked from commit eba6ce677b5d839ca90182e65f0eec7db0d92ed3)
(cherry picked from commit 6c48a2a93dfc4e102e888b02d8c5c097ed4ddadf)
(cherry picked from commit bc3863ac59326b113dc6627d078b853e78da7a81)