net: wireless: bcmdhd: fix enqueue and dequeue of deferred work framework

- increase priority work fifo size to 16
- align deferred work data to the power of two
- check for enough room before enqueue to avoid incomplete data
- check for enough data before dequeue to avoid incomplete data
- proper handling of enqueue and dequeue return values

BUG=28226991

Change-Id: I3be11134bb37bcb99157ff2f58cd7f775cd11260
Signed-off-by: Sreenath Sharma <sreenath.sharma@broadcom.com>