next: openrisc: Fix build

openrisc:defconfig fails to build in next-20140926 with the following error.

In file included from arch/openrisc/kernel/signal.c:31:0:
./arch/openrisc/include/asm/syscall.h: In function 'syscall_get_arch':
./arch/openrisc/include/asm/syscall.h:77:9: error: 'EM_OPENRISC' undeclared

Fix by moving EM_OPENRISC to include/uapi/linux/elf-em.h.

Fixes: ce5d1128 ("ARCH: AUDIT: implement syscall_get_arch for all arches")
Cc: Eric Paris <eparis@redhat.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Eric Paris <eparis@redhat.com>