hw/net/lan9118: log [read|write]b when mode_16bit is enabled rather than abort

This patch replaces hw_error to guest error log for [read|write]b
accesses when mode_16bit is enabled. This avoids aborting qemu.

Fixes: 1248f8d4 ("hw/lan9118: Add basic 16-bit mode support.")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1433


Reported-by: Qiang Liu <cyruscyliu@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Qiang Liu <cyruscyliu@gmail.com>
Suggested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>