input: sensors : fix hrtimer deadlock

Rearming the timer resulting into kernel BUG.
start the timer after callback's job is done.
Also use safer hrtimer_try_to_cancel instead of
hrtimer_cancel.

Reported trace indicates that timer state is 3,
which is not the expected state.

Special cases:
0x03	callback function running and enqueued

so, it fails at below point in hrtimer.c when
timer rearmed (possibly) on  another CPU.

BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);

Change-Id: I8e798208c6efe5187521d5933654d8640d3b38aa
Signed-off-by: Kiran Raparthy <krapar@codeaurora.org>