kernel: Add CONFIG_TMPFS_XATTR to confidential kernel

During pull inside the guest, overlayfs expects xattrs.

Fixes: [guest-components#876](https://github.com/confidential-containers/guest-components/issues/876)

Signed-off-by: Jakub Ledworowski <jakub.ledworowski@intel.com>

tools/packaging/kernel/build-kernel.sh

@@ -293,6 +293,9 @@ get_kernel_frag_path() {
 		info "Enabling config for '${conf_guest}' confidential guest protection"
 		local conf_configs="$(ls ${arch_path}/${conf_guest}/*.conf)"
 		all_configs="${all_configs} ${conf_configs}"
+
+		local tmpfs_configs="$(ls ${common_path}/confidential_containers/tmpfs.conf)"
+		all_configs="${all_configs} ${tmpfs_configs}"
 	fi
 
 	if [[ "$force_setup_generate_config" == "true" ]]; then

tools/packaging/kernel/configs/fragments/common/confidential_containers/tmpfs.conf

@@ -0,0 +1 @@
+CONFIG_TMPFS_XATTR=y

tools/packaging/kernel/kata_config_version

@@ -1 +1 @@
-145
+146