xen/mmu: Fix compile errors introduced by x86/memblock mismerge.

The git commit d4bbf7e7


"Merge branch 'master' into x86/memblock" mismerged the 32-bit
section causing:

arch/x86/xen/mmu.c: In function ‘xen_setup_kernel_pagetable’:
arch/x86/xen/mmu.c:1855: error: expected ‘;’ before ‘)’ token
arch/x86/xen/mmu.c:1855: error: expected statement before ‘)’ token

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>