Fix a bug in HBD buffer size computation

Fix a bug in HBD buffer size computation

The value of use_highbitdepth flag is used for compute the size for
high bit depth buffer allocation, which should take value 0 or 1
depending on if the buffer is used for high bit depth or not.
Previously, the values is set to 8 or 0, this commit fixes the issue
and properly set the value for this flag to 1 or 0.

This cuts the size of highbitdepth buffer memory allocation to 2/9 of
the size prior to the fix.

Change-Id: I401518b5a6147e5d8a973e54f7ca6bc1892065e0