msm: mdss: hdmi: fix 4k resolution parsing

Fix the parsing logic for extended tag Y420 VDB (Vendor Data Block)
4K resolutions by correctly checking the offset of resolution ids.

Change-Id: I59f9a7be47ac3634b0df6936051236ff22247116
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>