samples: cellular: at_client: disable legacy shim

AT Client does not respond with the legacy shim enabled.
We need to disable it.

Signed-off-by: Maximilian Deubel <[email protected]>

Author: maxd-nordic

samples/cellular/at_client/prj.conf

@@ -24,3 +24,5 @@ CONFIG_UART_INTERRUPT_DRIVEN=y
 CONFIG_MAIN_STACK_SIZE=3072
 CONFIG_HEAP_MEM_POOL_SIZE=16384
 CONFIG_AT_MONITOR_HEAP_SIZE=512
+
+CONFIG_UART_NRFX_UARTE_LEGACY_SHIM=n