powerpc: Backout relocation changes.

Ugh.  I *hate* to back this change out, but these compiler flags don't
work for relocation on all versions of GCC.  I've not been able to
reproduce the environment in my setup (and hence, not been able to
find a combination that *does* work), so I've got no choice but to go
back to the old gcc flags and linker script.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>