ppc/pnv: Remove pnv_xive_vst_size() routine

ppc/pnv: Remove pnv_xive_vst_size() routine

pnv_xive_vst_size() tries to compute the size of a VSD table from the
information given by FW. The number of entries of the table are
deduced from the result and the MMIO regions of the ESBs and the END
ESBs are then resized accordingly with the computed value. This
reduces the number of elements that can be addressed by the ESB pages.

The maximum number of elements of a direct table can contain is simply:

   Table size / sizeof(XIVE structure)

An indirect table is a one page array of VSDs pointing to subpages
containing XIVE virtual structures and the maximum number of elements
an indirect table can contain :

   (PAGE_SIZE / sizeof(vsd)) * (PAGE_SIZE / sizeof(XIVE structure))

which gives us 16M for XiveENDs, 8M for XiveNVTs. That's more than the
associated VC and PC BARS can address.

The result returned by pnv_xive_vst_size() for indirect tables is
incorrect and can not be used to reduce the size of the MMIO region of
a XIVE resource using an indirect table, such as ENDs in skiboot.

Remove pnv_xive_vst_size() and use a simpler form for direct tables
only. Keep the resizing of the MMIO region for direct tables only as
this is still useful for the ESB MMIO window.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20191115162436.30548-4-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>