base: genlock: Correct the lock file reference count.

genlock_get_fd_handle API creates a new FD and attaches
it to lock file and shares this FD to second process.
Now, two file descriptor are pointing to same file.
If one FD is closed, lock file will be closed. This
changes add a extra reference to lock file as new FD
has been attached. Taking this reference will make sure
that file doesn't get close. This refrence will go when
client will call close on this FD.

Change-Id: I3524bed5ededd89d43ca6d8b85df11c85c03c1e3
Signed-off-by: Deepak Kumar <dkumar@codeaurora.org>