AudioService: reduce EU volume warning thresdhold for USB headsets

Take into account additional gain due to simultaneous application of
EQ and bass boost by substracting 7dB from current warning message threshold.

Bug: 65225835
Test: check warning displayed when playing over USB headset after boot when
no SIM is present

Change-Id: I1bfcbf571d72122f4df6ff5e40be227c42d555e3
(cherry picked from commit 0e5deb3967398834c9d2321b31d3c56b380e98b5)
(cherry picked from commit 630f37a4ad13126d0bbdaa47052177e2c43c358f)
1 file changed