pdl: remove “checksum start precedes checksum field” lint

This lint is wrong, it is okay for the checksum start to start before
the checksum field itself. We have real files in the wild that uses
this construct, such as l2cap_packets.pdl.

Bug: 238865051
Test: atest pdl_inline_tests
(cherry picked from https://android-review.googlesource.com/q/commit:fbc2d570ba455099129905190e010149eb75e4f8)
Merged-In: I5d709a0fefdbdede704f799b46a20f523459d604
Change-Id: I5d709a0fefdbdede704f799b46a20f523459d604