Revert: ksud, kernel: Pick some upstream changes and remove unused functions

* Upstream commit:
f130f7572f

Signed-off-by: Faris <rsuntk@yukiprjkt.my.id>

userspace/ksud/src/defs.rs

@@ -38,4 +38,5 @@ pub const KSU_BACKUP_DIR: &str = WORKING_DIR;
 pub const KSU_BACKUP_FILE_PREFIX: &str = "ksu_backup_";
 pub const BACKUP_FILENAME: &str = "stock_image.sha1";
 
+pub const NO_TMPFS_PATH: &str = concatcp!(WORKING_DIR, ".notmpfs");
 pub const NO_MOUNT_PATH: &str = concatcp!(WORKING_DIR, ".nomount");