Fix compilattion issues in MojDbQuotaCheck.cpp

:Release Notes:
Fix const char* to char* convertion errors
Use operator== for MojString

:Detailed Notes:

:Testing Performed:
Compiled and tested localy.

:QA Notes:

:Issues Addressed:
[BHV-2044] [DB8] We need to inform warning message of quota level when service or application subscribe.

Open-webOS-DCO-1.0-Signed-off-by: Maksym Sditanov <maxim.sditanov@lge.com>

Change-Id: I1988b9465ff39e626003d31f1bd2f3333c5ad81b
Reviewed-on: https://g2g.palm.com/5964
Reviewed-by: DCO Verification
Tested-by: Maksym Sditanov <maxim.sditanov@lge.com>
Reviewed-by: Olexandr Solomakha <oleksander.solomakha@lge.com>
Reviewed-by: Maksym Sditanov <maxim.sditanov@lge.com>