Improvement for MikroTik RouterOS inventory

I add discovery in inventory model for MikroTik RouterOS

• 'entPhysicalModelName' => $mtxrBoardName – allow to search by alternative name (for example "wap ac")
• 'entPhysicalAssetID' => $mtxrLicSoftwareId – same as asset_tag on device
• 'entPhysicalFirmwareRev' => $mtxrFirmwareVersion – version of routerBOOT (boot loader)
• 'entPhysicalSoftwareRev' => $mtxrLicVersion – same as version on device