AudioPolicyManager: improve selectOutput functional flag matching

Prefer outputs with fewer unmatched functional flags.
Avoids assigning the audio stream to the VoIP output when
 - Primary output: 24, 32 or float
 - VoIP output: 16 bit

Bug: 200293124
Test: build pass
Signed-off-by: Carter Hsu <carterhsu@google.com>
Change-Id: I79d7429e9ef9c6fa02a7e7ba5f8e221ed81af423