audio: do not check for mode_in_communication for voip flags

This patch removes the unnecessary check conditions for
MODE_IN_COMMUNICATION and rely on the audiopolicymanager to set the voip
flags only for voice call based on stream types.

Bug: 62782025
Test: manual voip mo and mt calls tests
Change-Id: I7e22bc5c96c5429821cd4f4bade1acf6ba317ebc
Signed-off-by: David Lin <dtwlin@google.com>