hw/remote: Fix vfu_cfg trace offset format

hw/remote: Fix vfu_cfg trace offset format

The printed offset value is prefixed with 0x, but was actually printed
in decimal. To spare others the confusion, adjust the format specifier
to hexadecimal.

Signed-off-by: Mattias Nissler <mnissler@rivosinc.com>
Reviewed-by: Jagannathan Raman <jag.raman@oracle.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(cherry picked from commit 5fb9e8295531f957cf7ac20e89736c8963a25e04)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>