uprobes: Change handle_swbp() to expose bp_vaddr to handler_chain()

Change handle_swbp() to set regs->ip = bp_vaddr in advance, this is
what consumer->handler() needs but uprobe_get_swbp_addr() is not
exported.

This also simplifies the code and makes it more consistent across
the supported architectures. handle_swbp() becomes the only caller
of uprobe_get_swbp_addr().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>

arch/x86/kernel/uprobes.c

@@ -681,7 +681,6 @@ static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
 			continue;
 
 		if (auprobe->insn[i] == 0x90) {
-			regs->ip = uprobe_get_swbp_addr(regs);
 			regs->ip += i + 1;
 			return true;
 		}