Fix collateral damage to top level Makefile

The patch named "powerpc/mpc5121: Add clock driver", also contained
an unrelated and bogus change to the top-level makefile.  This patch
backs out the bad bit.

SHA1 of offending patch: 137e9590

)

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Repented-by: John Rigby <jrigby@freescale.com>
[ Heh. Normally I pick these out from the diffstats, but I guess
  I've grown to trust the ppc tree too much ;)   - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>