sample applications should not set exit_code as return statement of functions

[RonEld]

As commented in #199 (comment)
internal functions return code should be set to a variable different than exit_code.
It's not a functionality bug, but it shows bad practice

[andresag01]

I have created the PR #221 to fix the issue reported here.

[ciarmcom]

@RonEld thank you for raising this issue.Please take a look at the following comments:

Could you add some more detail to the description? A good description should be at least 25 words.
What target(s) are you using?
What toolchain(s) are you using?
What version of Mbed OS are you using (tag or sha)?
It would help if you could also specify the versions of any tools you are using?
How can we reproduce your issue?

NOTE: If there are fields which are not applicable then please just add 'n/a' or 'None'.This indicates to us that at least all the fields have been considered.
Please update the issue header with the missing information, the issue will not be mirroredto our internal defect tracking system or investigated until this has been fully resolved.

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?

[ciarmcom]

@RonEld it has been 5 days since the last reminder. Could you please update the issue header as previously requested?