applications: serial_lte_modem: Use downstream UART backend#23163

rlubos merged 1 commit intonrfconnect:mainnrfconnect/sdk-nrf:mainfrom

MarkusLassila:slm-downstream-uart-modem-backendMarkusLassila/sdk-nrf:slm-downstream-uart-modem-backendCopy head branch name to clipboard