powerpc: Remove BITOP_MASK and BITOP_WORD from asm/bitops.h

Replace BITOP_MASK and BITOP_WORD with BIT_MASK and BIT_WORD defined
in linux/bitops.h and remove BITOP_* which are not used anymore.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>