Fix acl support bits for GPFS FSAL.

Ganesha1.5 reported that it supports both 'ALLOW' and 'DENY' ace types.
The current code depends on an FSAL call, and many FSALs report that they
only support 'ALLOW' ace type! Due to a bug or a feature, Linux NFS
client supports NFS4 ACLs with a server if and only if the server
supports both 'ALLOW' and 'DENY' type ACEs. This means that Linux NFS
client doesn't support any form of NFS4 ACLs with Ganesha2.1 server.
GPFS indeed supports both 'ALLOW' and 'DENY' types, and this patch fixes
reporting both 'ALLOW' and 'DENY' bits.