x86: replace '||' usage in the linker script

x86: replace '||' usage in the linker script

With '|'. The result is the same, and the later works with lld. Fixes
the following error when building Xen with lld:

ld    -melf_x86_64_fbsd  -T xen.lds -N prelink.o --build-id=sha1 \
    /root/src/xen/xen/common/symbols-dummy.o -o /root/src/xen/xen/.xen-syms.0
ld: error: xen.lds:260: malformed number: |
>>> ASSERT(__image_base__ > (((((((((261 >> 8) * 0xffff000000000000) | (261 << 39))) + ((1 << 39) / 2)) + (64 << 30)) + (1 << 30)) + (1 << 30))) ||
>>>                                                                                                                                               ^

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>