drm/i915/audio: Consider fractional vdsc bpp while computing tu_data

MTL+ supports fractional compressed bits_per_pixel, with precision of
1/16. This compressed bpp is stored in U6.4 format.
Accommodate the precision during calculation of transfer unit data
for hblank_early calculation.

v2:
-Fix tu_data calculation while dealing with U6.4 format. (Stan)

v3:
-Use BPP_X16_FMT to print vdsc bpp.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Sui Jingfeng <suijingfeng@loongson.cn>
Link: https://patchwork.freedesktop.org/patch/msgid/20231110101020.4067342-5-ankit.k.nautiyal@intel.com