s3/smbd: fix access checks in set_ea_dos_attribute()

s3/smbd: fix access checks in set_ea_dos_attribute()

We wanted to set the DOS attributes and failed with permission denied
from the VFS/kernel/filesystem. Next thing we wanna do here is override
this if either

- "dos filemode = true" is set and the security descriptor gives the
  user write access or if

- the stored security descriptor has FILE_WRITE_ATTRIBUTES

The former was working, but the latter was not implemented at all.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=12995

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>