openat2: introduce EFTYPE error code

openat2: introduce EFTYPE error code

Introduce a new error code EFTYPE for wrong file type operations.
EFTYPE is already used in BSD systems like FreeBSD and macOS.

This will be used by the upcoming OPENAT2_REGULAR flag support to
return a specific error when a path doesn't refer to a regular file.

Signed-off-by: Dorjoy Chowdhury <dorjoychy111@gmail.com>
Link: https://patch.msgid.link/20260328172314.45807-2-dorjoychy111@gmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Aleksa Sarai <aleksa@amutable.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>