memblock: add functions to convert allocated pointers between virt/phys

vm/memblock.c

@@ -404,3 +404,13 @@ void __next_memory_region(memblock_iter_t *it, memblock_type_t *type_a, memblock
 	/* ULLONG_MAX signals the end of the iteration */
 	it->__idx = ITER_END;
 }
+
+phys_addr_t memblock_virt_to_phys(void *p)
+{
+	return (phys_addr_t)p - memblock.m_voffset;
+}
+
+void *memblock_phys_to_virt(phys_addr_t p)
+{
+	return (void *)(p + memblock.m_voffset);
+}