linux(4): Return ENODATA from getxattr syscalls instead of EPERM

On Linux ENODATA mean the named attribute does not exist, or the
process has no access to this attribute.

Reported by: zirias
PR: 273517
Tested by: zirias
MFC after: 1 week

(cherry picked from commit 4d59b790553ef75b9a4b6a673eab3354f3d012b3)