fix fs/nfs/nfsroot.c compilation

This fixes the following compile error caused by commit
f9247273cb69ba101877e946d2d83044409cc8c5 ("UFS: add const to parser
token table"):

    CC      fs/nfs/nfsroot.o
  /home/bunk/linux/kernel-2.6/git/linux-2.6/fs/nfs/nfsroot.c:130: error: tokens causes a section type conflict
  make[3]: *** [fs/nfs/nfsroot.o] Error 1

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>