drm/i915/xe3p_lpd: Extend FBC support to UINT16 formats

drm/i915/xe3p_lpd: Extend FBC support to UINT16 formats

Starting Xe3p_LPD, FBC is supported on UINT16 formats as well. Also
UINT16 being a 64bpp format, will use cpp of 8 for cfb stride and thus
size calculations.

v2: simplify getting the cpp per format (Ville)
    simplify the pixel format is valid for xe3p_lp (Vinod)

Cc: Shekhar Chauhan <shekhar.chauhan@intel.com>
BSpec: 68881, 68904, 69560
Signed-off-by: Sai Teja Pottumuttu <sai.teja.pottumuttu@intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patch.msgid.link/20251027134001.325064-2-vinod.govindapillai@intel.com