ssb: trivial: use u8 for chip_rev (it's mask is 0xF)

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/linux/ssb/ssb.h b/include/linux/ssb/ssb.h
index 9659eff..7e99b34 100644
--- a/include/linux/ssb/ssb.h
+++ b/include/linux/ssb/ssb.h
@@ -308,7 +308,7 @@
 
 	/* ID information about the Chip. */
 	u16 chip_id;
-	u16 chip_rev;
+	u8 chip_rev;
 	u16 sprom_offset;
 	u16 sprom_size;		/* number of words in sprom */
 	u8 chip_package;