Move EM_ARCOMPACT and EM_ARCV2 to uapi/linux/elf-em.h

These should never have been defined in the arch tree to begin with, and
now uapi/linux/audit.h header is going to use EM_ARCOMPACT and EM_ARCV2
in order to define AUDIT_ARCH_ARCOMPACT and AUDIT_ARCH_ARCV2 which are
needed to implement syscall_get_arch() which in turn is required to
extend the generic ptrace API with PTRACE_GET_SYSCALL_INFO request.

Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Cc: Elvira Khabirova <lineprinter@altlinux.org>
Cc: Eugene Syromyatnikov <esyr@redhat.com>
Cc: Alexey Brodkin <alexey.brodkin@synopsys.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-audit@redhat.com
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>