powerpc/e500: switch to 64 bits PGD on 85xx (32 bits)

powerpc/e500: switch to 64 bits PGD on 85xx (32 bits)

At the time being when CONFIG_PTE_64BIT is selected, PTE entries are 64
bits but PGD entries are still 32 bits.

In order to allow leaf PMD entries, switch the PGD to 64 bits entries.

Link: https://lkml.kernel.org/r/ca85397df02564e5edc3a3c27b55cf43af3e4ef3.1719928057.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Peter Xu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>