m68k: remove inline asm from minix_find_first_zero_bit

As a preparation for moving minix bit operations from asm/bitops.h to
architecture independent code in minix filesystem, this removes inline asm
from minix_find_first_zero_bit() for m68k.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>