ksmbd: set file permission mode to match Samba server posix extension behavior

[ Upstream commit f6c2b201 ]

Set file permission mode to match Samba server posix extension behavior.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>