x86: setup_arch() && early_ioremap_init()

Looks like the setup.c unification missed the early_ioremap init from
the early_ioremap unification.  Unconditionally call early_ioremap_init().

needed for "x86/paravirt: groundwork for 64-bit Xen support".

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Mark McLoughlin <markmc@redhat.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>