linux/common-config: set NFS_FS=m

This is built in by default on aarch64, where the defconfig has a bad
habit of including way too much stuff. It's particularly bad in this
case, because it prevents NFS_FSCACHE being set, because FSCACHE is a
module — for NFS_FSCACHE, both NFS and FSCACHE have to be built in, or
both have to be modules.

Changed files
+1
pkgs
os-specific
linux
+1
pkgs/os-specific/linux/kernel/common-config.nix
···
NFSD_V4 = yes;
NFSD_V4_SECURITY_LABEL = yes;
NFS_FSCACHE = yes;
NFS_SWAP = yes;
NFS_V3_ACL = yes;
···
NFSD_V4 = yes;
NFSD_V4_SECURITY_LABEL = yes;
+
NFS_FS = module;
NFS_FSCACHE = yes;
NFS_SWAP = yes;
NFS_V3_ACL = yes;