QCamera2: HAL3: correct timestamp calculation in HFR mode

When the phone powers up for several days,
the timestamp (in ns, nano sec) of frames will exceed the
precision of float data type.

It will lead to incorrect timestamp calculation in
HFR batch mode. Use double instead

Ack-by: Gaoxiang Chen

BUG=29967243
BUG=24842044

Change-Id: I63598e56178b980fa817c1c77f77f0e6a005767b
1 file changed