fs/namespace.c: Fix typo in comment

replace 'permanetly' with 'permanently' in the comment &
replace 'propogated' with 'propagated' in the comment

Signed-off-by: Yuesong Li <liyuesong@vivo.com>
Link: https://lore.kernel.org/r/20240806034710.2807788-1-liyuesong@vivo.com


Signed-off-by: Christian Brauner <brauner@kernel.org>