Created separate memblock functions for virtual and physical memory allocation

sandbox/base/main.c

@@ -50,7 +50,7 @@ int main(int argc, const char **argv)
 	memblock_reserve(0x30000, 0x40000);
 	memblock_reserve(0x100000, 0x10000);
 
-	phys_addr_t alloc = memblock_alloc(512);
+	phys_addr_t alloc = memblock_alloc_phys(512);
 	printf("allocated 512 bytes at 0x%" PRIxPTR "\n", alloc);
 
 	printf("memory regions:\n");