zephyr: serial_recovery: Use Zephyr manifest zcbor files

Switches from using the zcbor files in-tree to using the ones that
are part of the zephyr manifest, this prevents using old and
potentially buggy versions of the zcbor library.

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>
diff --git a/boot/zephyr/CMakeLists.txt b/boot/zephyr/CMakeLists.txt
index 925d869..34a39db 100644
--- a/boot/zephyr/CMakeLists.txt
+++ b/boot/zephyr/CMakeLists.txt
@@ -239,9 +239,6 @@
   zephyr_sources(${BOOT_DIR}/zephyr/serial_adapter.c)
   zephyr_sources(${BOOT_DIR}/boot_serial/src/boot_serial.c)
   zephyr_sources(${BOOT_DIR}/boot_serial/src/serial_recovery_cbor.c)
-  zephyr_sources(${BOOT_DIR}/boot_serial/src/zcbor_decode.c)
-  zephyr_sources(${BOOT_DIR}/boot_serial/src/zcbor_encode.c)
-  zephyr_sources(${BOOT_DIR}/boot_serial/src/zcbor_common.c)
 
   zephyr_sources_ifdef(CONFIG_BOOT_MGMT_ECHO ${BOOT_DIR}/boot_serial/src/serial_recovery_echo.c)
 
diff --git a/boot/zephyr/Kconfig.serial_recovery b/boot/zephyr/Kconfig.serial_recovery
index 92d0da0..aba2d58 100644
--- a/boot/zephyr/Kconfig.serial_recovery
+++ b/boot/zephyr/Kconfig.serial_recovery
@@ -14,6 +14,7 @@
 	select UART_INTERRUPT_DRIVEN
 	select BASE64
 	select CRC
+	select ZCBOR
 	help
 	  If y, enables a serial-port based update mode. This allows
 	  MCUboot itself to load update images into flash over a UART.