cmd: replace the cast of the memory access to a fixed bit type in itest

This patch fixes a bug that long word(.l) memory access in 'itest'
command reads the 8bytes of the actual memory on 64-bit architecture.
The cast to the memory pointer should use a fixed bit type.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

cmd/itest.c

@@ -65,13 +65,13 @@ static long evalexp(char *s, int w)
 		}
 		switch (w) {
 		case 1:
-			l = (long)(*(unsigned char *)buf);
+			l = (long)(*(u8 *)buf);
 			break;
 		case 2:
-			l = (long)(*(unsigned short *)buf);
+			l = (long)(*(u16 *)buf);
 			break;
 		case 4:
-			l = (long)(*(unsigned long *)buf);
+			l = (long)(*(u32 *)buf);
 			break;
 		}
 		unmap_physmem(buf, w);