memblock test: fix implicit declaration of function 'virt_to_phys'

Commit 94ff46d ("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 <richard.weiyang@gmail.com>
Link: https://lore.kernel.org/r/20240806010319.29194-1-richard.weiyang@gmail.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

Author: RichardWeiYang

tools/include/linux/mm.h

@@ -25,6 +25,12 @@ static inline void *phys_to_virt(unsigned long address)
 	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)