powerpc/32: Enable HW_BREAKPOINT on BOOK3S

BOOK3S also has DABR register and capability to handle data
breakpoints, so this patch enable it on all BOOK3S, not only 64 bits.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>