factory-setup: Remove C implementation of RTT

The debug builds use the rust implementation of RTT. The two
implementations cannot coexist. To be able to build debug builds of the
factory-setup the C imeplementation is therefore removed.

The factory-setup image is changed to use the second channel for API
calls, since the first is used for debug console.

Author: NickeZ

external/CMakeLists.txt

@@ -251,17 +251,6 @@ add_library(ctaes
 )
 target_include_directories(ctaes SYSTEM PUBLIC ctaes)
 
-add_library(rtt
-  SEGGER_RTT_V796b/RTT/SEGGER_RTT.c
-)
-target_compile_options(rtt PRIVATE "-Wno-cast-qual")
-# Define RTT config vars. The default DOWN buffer size (buffer for reading from host) is 64, which
-# is too small for our need.  The default UP buffer size (buffer for writing to host) is 1024, but
-# we define it anyway here in case the default changes.
-target_compile_definitions(rtt PUBLIC "BUFFER_SIZE_DOWN=(1024)" "BUFFER_SIZE_UP=(1024)")
-target_include_directories(rtt SYSTEM PUBLIC SEGGER_RTT_V796b/RTT SEGGER_RTT_V796b/Config)
-
-
 # optiga-trust-m
 # The below build instructions are loosely based on optiga-trust-m/tests/linux_i2c.cmake
 aux_source_directory(optiga-trust-m/src/cmd SRC_CMD_FILES)