Cabal2Ebuild.hs: fix error when converting "mtl ==2.0.* || >=2.1.1 && <2.2" depends

Before the patch agda-2.3.2.1.ebuild had:
    || ( >=dev-haskell/mtl-2.0:=[profile?] <dev-haskell/mtl-2.1:=[profile?] >=dev-haskell/mtl-2.1.1:=[profile?] <dev-haskell/mtl-2.2:=[profile?] )
After patch:
    || ( ( >=dev-haskell/mtl-2.0:=[profile?] <dev-haskell/mtl-2.1:=[profile?] )
         ( >=dev-haskell/mtl-2.1.1:=[profile?] <dev-haskell/mtl-2.2:=[profile?] ) )

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>