xen/arm: setup: use maddr_to_mfn rather than _mfn(paddr_to_pfn(...))

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/arm/setup.c

@@ -268,8 +268,8 @@ void __init discard_initial_modules(void)
         if ( mi->module[i].kind == BOOTMOD_XEN )
             continue;
 
-        if ( !mfn_valid(_mfn(paddr_to_pfn(s))) ||
-             !mfn_valid(_mfn(paddr_to_pfn(e))))
+        if ( !mfn_valid(maddr_to_mfn(s)) ||
+             !mfn_valid(maddr_to_mfn(e)) )
             continue;
 
         dt_unreserved_regions(s, e, init_domheap_pages, 0);