ext: debug: segger: Add USE_SEGGER_RTT that enables RTT libraries.

This option allows to explicitly include Segger RTT libraries and
enables use of it for various subsystems. It is disabled by
default as it consumes more RAM.

Signed-off-by: Pavel Kral <pavel.kral@omsquare.com>

doc/tools/nordic_segger.rst

@@ -167,6 +167,7 @@ To use RTT, you will first need to enable it by adding the following lines in yo
 .. code-block:: text
 
    CONFIG_HAS_SEGGER_RTT=y
+   CONFIG_USE_SEGGER_RTT=y
    CONFIG_RTT_CONSOLE=y
 
 If you get no RTT output you might need to disable other consoles which conflict

drivers/console/Kconfig

@@ -117,7 +117,7 @@ config RAM_CONSOLE_BUFFER_SIZE
 
 config RTT_CONSOLE
 	bool "Use RTT console"
-	depends on HAS_SEGGER_RTT
+	depends on USE_SEGGER_RTT
 	select CONSOLE_HAS_DRIVER
 	help
 	  Emit console messages to a RAM buffer that is then read by the

ext/debug/segger/CMakeLists.txt

@@ -1,6 +1,6 @@
 
-zephyr_include_directories_ifdef(CONFIG_HAS_SEGGER_RTT .)
-zephyr_sources_ifdef(CONFIG_HAS_SEGGER_RTT
+zephyr_include_directories_ifdef(CONFIG_USE_SEGGER_RTT .)
+zephyr_sources_ifdef(CONFIG_USE_SEGGER_RTT
 	rtt/SEGGER_RTT.c
 	rtt/SEGGER_RTT_zephyr.c
 	)

ext/debug/segger/Kconfig

@@ -7,7 +7,16 @@
 config HAS_SEGGER_RTT
 	bool
 
-if HAS_SEGGER_RTT
+config USE_SEGGER_RTT
+    bool "Enable SEGGER RTT libraries."
+    depends on HAS_SEGGER_RTT
+    default n
+    help
+        Enable Segger J-Link RTT libraries for platforms that support it.
+        Selection of this option enable use of RTT for various subsytems.
+        Note that by enabling this option, RTT buffers consumes more RAM.
+
+if USE_SEGGER_RTT
 
 config SEGGER_SYSTEMVIEW
 	bool "Segger SystemView support"

subsys/logging/Kconfig

@@ -296,7 +296,7 @@ config LOG_BACKEND_UART
 
 config LOG_BACKEND_RTT
 	bool "Enable Segger J-Link RTT backend"
-	depends on HAS_SEGGER_RTT
+	depends on USE_SEGGER_RTT
 	default y
 	help
 	  When enabled backend will use RTT for logging. This backend works on per