DirectShow: Change parameter of qt_evr_pixelFormatFromD3DFormat() to DWORD

Fixes g++ warnings:
..\common\evr\evrhelpers.cpp: In function 'QVideoFrame::PixelFormat qt_evr_pixelFormatFromD3DFormat(D3DFORMAT)':
..\common\evr\evrhelpers.cpp:143:5: warning: case value '842094158' not in enumerated type 'D3DFORMAT {aka _D3DFORMAT}' [-Wswitch]
     case D3DFMT_NV12:
..\common\evr\evrhelpers.cpp:145:5: warning: case value '842094169' not in enumerated type 'D3DFORMAT {aka _D3DFORMAT}' [-Wswitch]
     case D3DFMT_YV12:

Change-Id: I11869144b34d848bd68434d3a062852608518978
Reviewed-by: Christian Stromme <christian.stromme@qt.io>