x86/LDT: Avoid warning in 32-bit builds with older gcc

x86/LDT: Avoid warning in 32-bit builds with older gcc

BUG() doesn't always imply "no return", and hence should be followed by
a return statement even if that's obviously (to a human) unreachable.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/5A8AF2AA02000078001A91E9@prv-mh.provo.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>