powerpc/64: Fix L1D cache shape vector reporting L1I values

It seems we didn't pay quite enough attention when testing the new cache
shape vectors, which means we didn't notice the bug where the vector for
the L1D was using the L1I values. Fix it, resulting in eg:

  L1I  cache size:     0x8000      32768B         32K
  L1I  line size:        0x80       8-way associative
  L1D  cache size:    0x10000      65536B         64K
  L1D  line size:        0x80       8-way associative

Fixes: 98a5f361 ("powerpc: Add new cache geometry aux vectors")
Cut-and-paste-bug-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Badly-reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>