sched/x86/32, kgdb: Don't use thread.ip in sleeping_thread_to_gdb_regs()

sched/x86/32, kgdb: Don't use thread.ip in sleeping_thread_to_gdb_regs()

Match 64-bit and set gdb_regs[GDB_PC] to zero.  thread.ip is always the
same point in the scheduler (except for newly forked processes), and will
be removed in a future patch.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1471106302-10159-2-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>