kernel: 6.1: Add missing config option DEVTMPFS_SAFE

Fixes build error when enabling CONFIG_KERNEL_DEVTMPFS in OpenWrt menuconfig.

Signed-off-by: Marius Dinu <[email protected]>

target/linux/generic/config-6.1

@@ -1479,6 +1479,7 @@ CONFIG_DEVPORT=y
 # CONFIG_DEVPTS_MULTIPLE_INSTANCES is not set
 # CONFIG_DEVTMPFS is not set
 # CONFIG_DEVTMPFS_MOUNT is not set
+# CONFIG_DEVTMPFS_SAFE is not set
 # CONFIG_DEV_DAX is not set
 # CONFIG_DGAP is not set
 # CONFIG_DGNC is not set