powerpc: Enable support for 32 bit MSI-X vectors

Some devices are not capable of addressing 64 bits
via DMA, which includes MSI-X vectors. This allows
us to ensure these devices use MSI-X vectors in
32 bit space.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240117214632.134539-1-brking@linux.vnet.ibm.com