Change mbedtls_platform_context parameter to NULL

[RonEld]

Description

mbedtls_platform_setup() and mbedtls_platform_teardown() now ignore the context parameter, since #7099 was merged. Changing the sent parameter to NULL, to avoid misleading.
This PR continues #7099

Pull request type

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

[0xc0170]

@RonEld Who should review these changes?

[RonEld]

@RonEld Who should review these changes?

I would say that @pan- should review the BLE part and @sbutcher-arm , @Patater or someone on their behalf should review the Mbed TLS part

[simonbutcher]

We really need, in addition to these changes, a test to test out the reference counting of the resource. Two stacked setup's, followed by a crypto test operation a teardown, another test operation and a teardown, or similar.

Not a blocker - so @RonEld - can you either add that test, or create a JIRA ticket and the team can do it at a later date.

[RonEld]

@sbutcher-arm

Not a blocker - so @RonEld - can you either add that test, or create a JIRA ticket and the team can do it at a later date.

Created IOTSSL-2502 to track this

[pan-]

Good for me on the BLE side.

[RonEld]

@0xc0170 Since this PR was reviewed by both @pan- and @sbutcher-arm , I think we can remove review request from @Patater
In addition, could you please start the CI? Although this is not a blocker for 5.10 , I would like to see it in 5.10,as a follow up of #7099 , unless it won't make it

[kjbracey]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 3043
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/7960/

Triggering tests

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

[mbed-ci]

Exporter Build : SUCCESS

Build number : 2659
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/7960/

[mbed-ci]

Test : SUCCESS

Build number : 2816
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/7960/2816