powerpc: Use asm-generic/bitops/le.h

The only difference between powerpc and asm-generic le-bitops is
test_bit_le().  Usually all bitops require a long aligned bitmap.
But powerpc test_bit_le() can take an unaligned address.

There is no special callsite of test_bit_le() that needs unaligned
access in powerpc as far as I can see.  So convert to use
asm-generic/bitops/le.h for powerpc.

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>