drm/edid: clean up cea_db_is_*() functions

drm/edid: clean up cea_db_is_*() functions

Abstract helpers for matching vendor data blocks and extended tags, and
use them to simplify all the cea_db_is_*() functions.

Take void pointer as parameter to allow transitional use for both u8 *
and struct cea_db *.

v2: Remove superfluous parens (Ville)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b6bb813afc35c763e744c6cdb4a787da3adf910b.1651569697.git.jani.nikula@intel.com