include/linux/dmar.h: replace single-char identifiers in macros

There are a few macros in IOMMU have single-char identifiers make the code
hard to read and debug.  Replace them with meaningful names.

Link: http://lkml.kernel.org/r/1559566783-13627-1-git-send-email-cai@lca.pwSigned-off-by: Qian Cai <cai@lca.pw>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/dmar.h

@@ -92,12 +92,14 @@ static inline bool dmar_rcu_check(void)
 
 #define	dmar_rcu_dereference(p)	rcu_dereference_check((p), dmar_rcu_check())
 
-#define	for_each_dev_scope(a, c, p, d)	\
-	for ((p) = 0; ((d) = (p) < (c) ? dmar_rcu_dereference((a)[(p)].dev) : \
-			NULL, (p) < (c)); (p)++)
-
-#define	for_each_active_dev_scope(a, c, p, d)	\
-	for_each_dev_scope((a), (c), (p), (d))	if (!(d)) { continue; } else
+#define for_each_dev_scope(devs, cnt, i, tmp)				\
+	for ((i) = 0; ((tmp) = (i) < (cnt) ?				\
+	    dmar_rcu_dereference((devs)[(i)].dev) : NULL, (i) < (cnt)); \
+	    (i)++)
+
+#define for_each_active_dev_scope(devs, cnt, i, tmp)			\
+	for_each_dev_scope((devs), (cnt), (i), (tmp))			\
+		if (!(tmp)) { continue; } else
 
 extern int dmar_table_init(void);
 extern int dmar_dev_scope_init(void);