ranged_breakpoint: don't use init_raw_breakpoint

ranged_breakpoint's ctor already sets the breakpoint's type to
bp_hardware_breakpoint.

Since this is a "regular" breakpoint, b->pspace should remain NULL.

Thus, the only thing init_raw_breakpoint is needed for, is to add the
breakpoint's location.  Do that directly.

Change-Id: I1505de94c3919881c2b300437e2c0da9b05f76bd