hdmitx: adjust edid parsing [1/2]

PD#SWPL-97387
BUG=244782420

Problem:
TVTS/2.4_R2 failed

Solution:
remove useless parsing code, and adjust
edid parsing and fallback policy
1.if edid checksum invalid in any block,
or header of cta extension block is 0,
then use fallback mode list
2.if base block header invalid, or
checksum invalid, then don't parse
base block except dtd / standard timing
3.for cta extension block, if block
byte0 != 0x2, it means not valid
extension block, skip parsing whole
block. if block byte1 <= 2, it means
that it's DVI block, skip parsing data
block, just parse DTD.
4.fallback mode list:
480p/720p/1080p60hz, RGB,8bit, and uplayer
should use 720p60hz RGB,8bit by default

Verify:
ah212

Signed-off-by: xiang.wu1 <xiang.wu1@amlogic.com>
Change-Id: I6e4b04888ce097846d18acaf3ba0df3e92313440