memblock test: fix implicit declaration of function 'virt_to_phys'

Commit 94ff46de4a73 ("memblock: Move late alloc warning down to phys
alloc") introduce the usage of virt_to_phys(), which is not defined in
memblock tests.

Define it in mm.h to fix the build error.

Signed-off-by: Wei Yang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mike Rapoport (Microsoft) <[e-mail]>

tools/include/linux/mm.h

···
 	return __va(address);
 }
 
+#define virt_to_phys virt_to_phys
+static inline phys_addr_t virt_to_phys(volatile void *address)
+{
+	return (phys_addr_t)address;
+}
+
 void reserve_bootmem_region(phys_addr_t start, phys_addr_t end, int nid);
 
 static inline void totalram_pages_inc(void)