video: msm: external: Limit HDMI to standard resolutions

The mako can't handle higher resolutions, even if detected, resulting
in errors like the following:

[ 1090.222005] mdp4_dtv_start: <ID=129 3840x2160 (1056,88,296), (8,10,72) 297MHz>
[ 1090.228597] Rate 297000000 for tv_src_clk is greater than highest Fmax

so limit the max resolution to HDMI_VFRMT_1920x1080p100_16_9

Change-Id: I3dcb5f7a49a8413680096b5419c9fa37e9e14587