Bluetooth: Fix to decrease power during OPP TX/RX

Bluetooth: Fix to decrease power during OPP TX/RX

Due to alarm timer implementation, bta_sys_idle OR bta_sys_busy call
was the overhead(eg. 7ms) on every OPP packet(TX/RX), which was causing
high power. Below optimization have been done in JV to decrease
power during OPP TX/RX
- If particular JV acl link is in sniff, only then use bta_sys_busy to
  trigger unsniff request.
- Start intermediate idle timer(1s) before starting actual idle sniff
  timer(bta_sys_idle).

CRs-fixed: 1028625
Change-Id: Ied1173776f9bf2dc89b8e84e68d6217932a01607