StageFright: Fix to handle software decoder crash, during playback.

For s/w video decoding, trying to access "stride" and
"slice-height" parameters without its prior initialization.
As a part of fix, these parameter are set at appropriate
place before its retrieval.

CRS-Fixed : 732893  <http://prism.qualcomm.com/CR/732893>
CRS-Fixed : 736625  <http://prism.qualcomm.com/CR/736625>
CRS-Fixed : 738797  <http://prism.qualcomm.com/CR/738797>
CRS-Fixed : 740944  <http://prism.qualcomm.com/CR/740944>

Change-Id: Ic2f4f9109523a81ed77fa63a942664fd3e791496