Did you have a look at the section "8.4.2 Using Checksum Exclusion" in "AN97060 PSoC® 4 BLE and PRoC™ BLE – Over-the-Air (OTA) Device Firmware Upgrade (DFU) Guide".
I have a similar build error for my CYBL11172-56LQXI for BLE. I get this error :
Build error: section i.smp_handle_secure_connection_only_mode loaded at [00023400,0002342b] overlaps section .cy_checksum_exclude loaded at [00023400,000236ff]
Can you provide a sample project, that would be a great help!
FYI: I am using No security for BLE on the security mode for now.