arm/xen: Drop duplicate define mfn_to_virt

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

arch/arm/include/asm/xen/page.h

@@ -12,7 +12,6 @@
 #include <xen/interface/grant_table.h>
 
 #define phys_to_machine_mapping_valid(pfn) (1)
-#define mfn_to_virt(m)			(__va(mfn_to_pfn(m) << PAGE_SHIFT))
 
 #define pte_mfn	    pte_pfn
 #define mfn_pte	    pfn_pte