[M/S][Barometer]Fix IIR register in BMP28x driver

Bug: 77659366

Test: 1. install Barometer Graph.apk from app store.
Test: 2. Turn on barometer, observe the output to see it stable
Test: 3. Turn off barometer, either take device to a place with
         a significantly different pressure (e.g. move up/down
         multiple floors in a tall building, or use pressure
         chamber, etc)
Test: 4. Turn on barometer, the good behavior is for the first
         readings to be accurate to the new pressure and the
         graph to therefore be relatively flat.

Change-Id: I13533ee2186e9d244a431bc1f145658f7781b12a