enc field is hidden behind BOOK3E_PAGESZ_XX macros, and when you look
closer you realise that this field is nothing else than the value of shift
minus ten.

So remove enc field and calculate tsize from shift field.

Also remove inc field which is unused.

Link: https://lkml.kernel.org/r/e99136779b5b0829c2c60d37f305a1410c65cf9b.1719928057.git.christophe.leroy@csgroup.euSigned-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>