Commit db1ffc32 ("qemu/bitops.h: add bitrev8 implementation") introduced
a bitrev8() function to reverse the bit ordering required for storing the
MAC address in the q800 PROM.

This function is not required since QEMU implements its own revbit8()
function which does exactly the same thing. Remove the extraneous
bitrev8() function and switch its only caller in hw/m68k/q800.c to
use revbit8() instead.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210725110557.3007-1-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>