m68k: sun3: Change led_pattern[] to unsigned char

The values stored in led_pattern[] are only used for passing to
sun3_leds(), which takes an "unsigned char".
Change the type of led_pattern[] accordingly, to reduce kernel size.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/794c5d543dbdae8336a13ef2459adafaaadb7d86.1695031620.git.geert@linux-m68k.org