[PowerPC] Revert ppc64le-aggregates.ll test changes from r227053

It appears we have different behavior with and without -mcpu=pwr8 even
with ppc64le defaulting to POWER8.  The failure appears as follows:

/home/bb/cmake-llvm-x86_64-linux/llvm-project/llvm/test/CodeGen/PowerPC/ppc64le-aggregates.ll:268:14: error: expected string not found in input
; CHECK-DAG: lfs 1, 0([[REG]])
             ^
<stdin>:497:11: note: scanning from here
 ld 3, .LC1@toc@l(3)
          ^
<stdin>:497:11: note: with variable "REG" equal to "3"
 ld 3, .LC1@toc@l(3)
          ^
<stdin>:514:2: note: possible intended match here
 lfs 1, 0(4)
 ^

Reverting this particular test case change.  Nemanja, please have a look
at the reason for the failure.

llvm-svn: 227055