nfs: add missing "posix" local_lock constant table definition

"mount -o local_lock=posix..." was broken by the mount API conversion
due to the missing constant.

Fixes: e38bb238 ("NFS: Convert mount option parsing to use functionality from fs_parser.h")
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/fs_context.c

@@ -94,6 +94,7 @@ enum {
 static const struct constant_table nfs_param_enums_local_lock[] = {
 	{ "all",		Opt_local_lock_all },
 	{ "flock",	Opt_local_lock_flock },
+	{ "posix",	Opt_local_lock_posix },
 	{ "none",		Opt_local_lock_none },
 	{}
 };