powerpc: Fix comment typos in arch/powerpc/include/asm/bitops.h

powerpc: Fix comment typos in arch/powerpc/include/asm/bitops.h

In arch/powerpc/include/asm/bitops.h, the comments about bit numbers in
large (> 1 word) bitmaps have two typos:
- On ppc64 system, the LSB of the 4th word should be bit 192 rather than
  196, because if it's bit 196, bit 192-195 will be missing in the
  bitmap.
- On ppc32 system, the LSB of the second word should be bit 32 rather
  than 31, because bit 31 is already in the first word.

This patch fixes these typos.

Signed-off-by: Boqun Feng <boqun.feng@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>