qcom: smb138x: Reduce die temperature samples for initial readings

Die temperature samples 10 times to take average to reduce error,
which extends time in reading and causes delay during boot up, where
the data is not really insterested.

To improve it, only take one sample for the first few user temp
readings.

Change-Id: Ifc10de8a624f1d50d303673ff553d4801337481b
Signed-off-by: Harry Yang <harryy@codeaurora.org>