Revert "Follow change in patSynSig"

This reverts commit e811b00837d19340047ad83273b4aa2dc2534dd8.
since the respective change isn't in GHC 7.8.3 yet
GHC 7.8: follow changes in PatSyn and LHsBindsLR

Signed-off-by: Austin Seipp <aseipp@pobox.com>