memtest: Fix memspeed access size

The move to libbase reverted the type of the pointer
from long to int.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

litex/soc/software/libbase/memtest.c

@@ -164,7 +164,7 @@ int memtest_data(unsigned int *addr, unsigned long size, int random)
 
 void memspeed(unsigned int *addr, unsigned long size, bool read_only)
 {
-	volatile unsigned int *array = addr;
+	volatile unsigned long *array = (unsigned long *)addr;
 	int i;
 	unsigned int start, end;
 	unsigned long write_speed = 0;