nfsd4: permit layoutget of executable-only files

[ Upstream commit 66282ec1cf004c09083c29cb5e49019037937bbd ]

Clients must be able to read a file in order to execute it, and for pNFS
that means the client needs to be able to perform a LAYOUTGET on the file.

This behavior for executable-only files was added for OPEN in commit
a043226b "nfsd4: permit read opens of executable-only files".

This fixes up xfstests generic/126 on block/scsi layouts.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>