fs: move initializing f_mode before file_ref_init()

fs: move initializing f_mode before file_ref_init()

The comment above file_ref_init() says:
"We're SLAB_TYPESAFE_BY_RCU so initialize f_ref last."
but file_set_fsnotify_mode() was added after file_ref_init().

Move it right after setting f_mode, where it makes more sense.

Fixes: 711f9b8fbe4f4 ("fsnotify: disable pre-content and permission events by default")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://patch.msgid.link/20260109211536.3565697-1-amir73il@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>