This is the initial step for converting singlestep handling via ptrace
over to hw_breakpoints.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Presently the hw_breakpoint code is the primary notifier dispatch for
breakpoint traps, although it's only UBC traps that are of particular
interest there. This patches in a check to allow non-UBC generated
breakpoints to pass through down the remainder of the notifier chain,
giving things like kgdb a chance at getting notified.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

The event callback handling has been removed in favour of going through a
generic event handler to handle overflows. Follows the x86 change.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This adds preliminary support for the SH-4A UBC to the hw-breakpoints API.
Presently only a single channel is implemented, and the ptrace interface
still needs to be converted. This is the first step to cleaning up the
long-standing UBC mess, making the UBC more generally accessible, and
finally making it SMP safe.

An additional abstraction will be layered on top of this as with the perf
events code to permit the various CPU families to wire up support for
their own specific UBCs, as many variations exist.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>