Add missing carriage returns to fault handler

[kjbracey]

Description

Fault handler was outputting just LFs between lines, when standard
terminals require CR+LF, leading to messy output.

Pull request type

[ ] Fix
[ ] Refactor
[ ] New target
[ ] Feature
[X] Breaking change

Marked "breaking change" because it could conceivably trip up some automation relying on parsing fault handler output that expects odd formatting - it does change the output.

Seems unlikely though, as most normal output will be CR+LF terminated, either because apps do \r\n manually (yuck) or because platform.stdio-convert-newlines is turned on as it should be. So anything parsing general output will be expecting that.

[adbridge]

@SenRamakri we are still awaiting your review on this PR, could you please do so asap. Thanks.

[SenRamakri]

Looks good, by the way, I'm in the process of refactoring this code as part of error handling. So this may get moved elsewhere.

[0xc0170]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 1906
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/6654/

Triggering tests

/morph test
/morph uvisor-test
/morph export-build
/morph mbed2-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 1553
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/6654/

[mbed-ci]

Test : FAILURE

Build number : 1724
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/6654/1724

[0xc0170]

We will investigate the failure (not related here, noticed it in the last day)

/morph test

[mbed-ci]

Test : FAILURE

Build number : 1736
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/6654/1736

[0xc0170]

Fix for the last test is now on master, restarting

/morph test

[mbed-ci]

Test : SUCCESS

Build number : 1747
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/6654/1747