Add Laird BL654 as a new MTB target.

[ashok-rao]

Description

Adding Laird BL654 as a new MTB module target.

Pull request type

[ ] Fix
[ ] Refactor
[x] Target update
[ ] Functionality change
[ ] Breaking change

New Target.

Greentea: All tests passing on all 3 toolchains. Logs attached below.
BL654_ARMCC_GT_Pass_log.txt
BL654_GCC_GT_Pass_log.txt
BL654_IAR_GT_Pass_log.txt

@0xc0170 @cmonr : Can you please review? Please note that this target is not "physically" available in CI yet as it is a new MTB/MCB target. Also, the 1st commit was to bring my fork up-to-date with master of Mbed OS. Not sure if this would create any merge conflicts or not. Can you please check? Thanks.

[cmonr]

Hi Ashok,

The first change will likely cause some weird issues with the release process. When updating a branch, we recommend rebasing on top of an updated master branch. Something like the following:

git checkout dev-branch
__work is done__
git checkout master
git fetch upstream master
git rebase upstream/master
git checkout dev-branch
git rebase upstream/master

Where upstream is a remote added with the following command:
git remote add upstream https://github.com/ARMmbed/mbed-os

[ashok-rao]

Thanks @cmonr .. that's the exact process I follow, but I mixed things up this time around. What do you recommend we do with this PR now? I'm Ok to start afresh if that helps..

[cmonr]

@ashok-rao Whatever is easier for you. You can modify this PR or open a new one, either is fine.

[0xc0170]

why are these commented out?

[ashok-rao]

@0xc0170 : Thanks. Because the SPIS pins are not brought out on the MCB/MTB .. I kept it there (in comments) so that it may help end users to add these if they decide to bring these pins out from the module on their respective boards..

[ashok-rao]

@cmonr / @0xc0170 : Closing this one. New PR opened #8454 with single commit. Thanks!