The DP CTS test for EDID last block checksum expects the checksum for
the last block, invalid or not. Skip the validity check.

For the most part (*), the EDIDs returned by drm_get_edid() will be
valid anyway, and there's the CTS workaround to get the checksum for
completely invalid EDIDs. See commit 7948fe12 ("drm/msm/dp: return
correct edid checksum after corrupted edid checksum read").

This lets us remove one user of drm_edid_block_valid() with hopes the
function can be removed altogether in the future.

(*) drm_get_edid() ignores checksum errors on CTA extensions.

Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Kuogee Hsieh <khsieh@codeaurora.org>
Cc: Marijn Suijten <marijn.suijten@somainline.org>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/555361/
Link: https://lore.kernel.org/r/20230901142034.580802-1-jani.nikula@intel.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>