xen/p2m: avoid unneccesary TLB flush in m2p_remove_override()

In m2p_remove_override() when removing the grant map from the kernel
mapping and replacing with a mapping to the original page, the grant
unmap will already have flushed the TLB and it is not necessary to do
it again after updating the mapping.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

arch/x86/xen/p2m.c

@@ -1003,7 +1003,6 @@ int m2p_remove_override(struct page *page,
 
 			set_pte_at(&init_mm, address, ptep,
 					pfn_pte(pfn, PAGE_KERNEL));
-			__flush_tlb_single(address);
 			kmap_op->host_addr = 0;
 		}
 	}