st/va Avoid VBR bitrate calculation overflow v2

VBR bitrate calc needs 64 bits at high rates.

v2: use float.

Signed-off-by: Andy Furniss <adf.lists@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Cc: mesa-stable@lists.freedesktop.org
1 file changed