hw/net/lan9118: Fix RX Status FIFO PEEK value

A copy-and-paste error meant that the return value for register offset 0x44
(the RX Status FIFO PEEK register) returned a byte from a bogus offset in
the rx status FIFO. Fix the typo.

Cc: qemu-stable@nongnu.org
Fixes: https://bugs.launchpad.net/qemu/+bug/1904954


Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20210108180401.2263-2-peter.maydell@linaro.org