edid: Use sizeof() in cea_is_hdmi_vsdb_present()

We should not use an open-coded value here. Use sizeof() instead.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Coverity (CID: 163252)
Fixes: 43c6bdd0 (edid: Add HDMI flag to timing info)
1 file changed