hw/remote/vfio-user: Fix config space access byte order

hw/remote/vfio-user: Fix config space access byte order

PCI config space is little-endian, so on a big-endian host we need to
perform byte swaps for values as they are passed to and received from
the generic PCI config space access machinery.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: Mattias Nissler <mnissler@rivosinc.com>
Message-ID: <20240507094210.300566-6-mnissler@rivosinc.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
(cherry picked from commit e6578f1f68a0e90789a841ada532c3e494c9a04c)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>