BLE: suppress error when no path is passed in for ble security db

[paul-szczepanek-arm]

Summary of changes

Fixing #14832
If no security db path is passed in more error should be printed. This avoids trying to init the db with null path.

Impact of changes

Migration actions required

Documentation

none

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Pull request type

[x] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

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Test results

[] No Tests required for this change (E.g docs only update)
[x] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

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Reviewers

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[ciarmcom]

@paul-szczepanek-arm, thank you for your changes.
@ARMmbed/mbed-os-maintainers please review.

[ciarmcom]

This pull request has automatically been marked as stale because it has had no recent activity. @ARMmbed/mbed-os-maintainers, please start CI to get the PR merged.

[0xc0170]

CI started

[mbed-ci]

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