mgmt/mcumgr: Remove APP_LINK_WITH_MCUMGR Kconfig option

This option is not actually doing anything.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
diff --git a/subsys/mgmt/mcumgr/Kconfig b/subsys/mgmt/mcumgr/Kconfig
index 7d8737b..ad58280 100644
--- a/subsys/mgmt/mcumgr/Kconfig
+++ b/subsys/mgmt/mcumgr/Kconfig
@@ -28,14 +28,6 @@
 	help
 	  Scheduling priority of the MCUMGR SMP work queue.
 
-config APP_LINK_WITH_MCUMGR
-	bool "Link 'app' with MCUMGR"
-	default y
-	help
-	  Add MCUMGR header files to the 'app' include path. It may be
-	  disabled if the include paths for MCUMGR are causing aliasing
-	  issues for 'app'.
-
 rsource "mgmt/Kconfig"
 
 config MGMT_MAX_MAIN_MAP_ENTRIES