ANDROID: GKI: set CONFIG_BLK_DEV_LOOP_MIN_COUNT to 16

CONFIG_BLK_DEV_LOOP_MIN_COUNT must be at least 16 in order
to pass VTS.

Bug: 158309019
Signed-off-by: Steve Muckle <smuckle@google.com>
Change-Id: I70df397f6340e15222cee9e5e0fc2125b2a17dad