staging/lustre: use __noreturn for lbug_with_loc

fixes sparse error:
drivers/staging/lustre/lustre/libcfs/linux/linux-debug.c:149:6: error:
symbol 'lbug_with_loc'redeclared with different type (originally declared at
drivers/staging/lustre/lustre/libcfs/linux/../../../include/linux/libcfs/libcfs_private.h:82)
- different modifiers

Use the __noreturn macro instead of __attribute__((noreturn))
The macro is exactly that but its usage seems more common and
it is bit more readable.

Signed-off-by: Juston Li <juston.h.li@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>