net: fbnic: Fix page chunking logic when PAGE_SIZE > 4K

net: fbnic: Fix page chunking logic when PAGE_SIZE > 4K

The HW always works on a 4K page size. When the OS supports larger
pages, we fragment them across multiple BDQ descriptors.
We were not properly incrementing the descriptor, which resulted in us
specifying the last chunks id/addr and then 15 zero descriptors. This
would cause packet loss and driver crashes. This is not a fix since the
Kconfig prevents use outside of x86.

Signed-off-by: Dimitri Daskalakis <dimitri.daskalakis1@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20251013211449.1377054-2-dimitri.daskalakis1@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>