userspace: remove APP_SHARED_MEM Kconfig

This is an integral part of userspace and cannot be used
on its own. Fold into the main userspace configuration.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
diff --git a/scripts/gen_app_partitions.py b/scripts/gen_app_partitions.py
index 66c5795..1433c17 100644
--- a/scripts/gen_app_partitions.py
+++ b/scripts/gen_app_partitions.py
@@ -16,7 +16,7 @@
 # This script will create sections and linker variables to place the
 # application shared memory partitions.
 # these are later read by the macros defined in app_memdomain.h for
-# initialization purpose when APP_SHARED_MEM is enabled.
+# initialization purpose when USERSPACE is enabled.
 data_template = """
 		/* Auto generated code do not modify */
 		SMEM_PARTITION_ALIGN(data_smem_{0}_bss_end - data_smem_{0}_start);