Remove Segger RTT from pico-btstack

We now have this in the SDK so adding it again in pico-btstack leads to
link errors.

Author: peterharperuk

src/rp2_common/pico_btstack/CMakeLists.txt

@@ -28,7 +28,6 @@ if (EXISTS ${PICO_BTSTACK_PATH}/${BTSTACK_TEST_PATH})
     target_sources(pico_btstack_base INTERFACE
         ${PICO_BTSTACK_PATH}/3rd-party/micro-ecc/uECC.c
         ${PICO_BTSTACK_PATH}/3rd-party/rijndael/rijndael.c
-        ${PICO_BTSTACK_PATH}/3rd-party/segger-rtt/SEGGER_RTT.c
         ${PICO_BTSTACK_PATH}/3rd-party/segger-rtt/SEGGER_RTT_printf.c
         ${PICO_BTSTACK_PATH}/platform/embedded/btstack_tlv_flash_bank.c
         ${PICO_BTSTACK_PATH}/platform/embedded/hci_dump_embedded_stdout.c