fw_lab_triage_helper: apply shell style guide

Applied the following aspects of the style guide:

Don't use a file extension (not mandatory, but strongly preferred).
Start the file with a description of contents.
Put dos on the same line as the if/for/while.
Use the parameter expansion assignment syntax for setting a default value.
Have separate declaration and assigment statements when the assignment
value is provided by a command substitution.
Use embedded newlines in long strings.
Only use caps for constants variable names.
Use a main function (since there is at least one other function).

Also misc cleanups.

BUG=None
TEST=ran script against the faft-cr50 pool and faft-test pool

Change-Id: I62a78a473d9d4d9c0dc5fde7463e0e3ef8f81045
Reviewed-on: https://chromium-review.googlesource.com/1570306
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Kevin Shelton <kmshelton@chromium.org>
Reviewed-by: Mary Ruthven <mruthven@chromium.org>
2 files changed