diag: Fix diag hdlc decoding support for messages starting with 0x7e

Currently, when an hdlc encoded message is processed by diag and it
encounters a 0x7e, it considers that the end of the message. Make changes
to support messages starting with 0x7e.

Also, when a message is encountered that is too short, rate limit the
the associated error message to prevent flooding of messages.

CRs-Fixed: 456952
Change-Id: Ie01387479ca8fb0ae290400b1adc5627faab80d3
Signed-off-by: Dixon Peterson <dixonp@codeaurora.org>
2 files changed