regmap: Add a helper function for regcache sync test

We're going to add another "does this register need syncing?" check, so
rather than repeating it in three places, we'll separate all of the
relevant logic into a helper function.

Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 7eb7b3b..c58493e 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -249,6 +249,18 @@
 	return 0;
 }
 
+static bool regcache_reg_needs_sync(struct regmap *map, unsigned int reg,
+				    unsigned int val)
+{
+	int ret;
+
+	/* Is this the hardware default?  If so skip. */
+	ret = regcache_lookup_reg(map, reg);
+	if (ret >= 0 && val == map->reg_defaults[ret].def)
+		return false;
+	return true;
+}
+
 static int regcache_default_sync(struct regmap *map, unsigned int min,
 				 unsigned int max)
 {
@@ -266,9 +278,7 @@
 		if (ret)
 			return ret;
 
-		/* Is this the hardware default?  If so skip. */
-		ret = regcache_lookup_reg(map, reg);
-		if (ret >= 0 && val == map->reg_defaults[ret].def)
+		if (!regcache_reg_needs_sync(map, reg, val))
 			continue;
 
 		map->cache_bypass = 1;
@@ -613,10 +623,7 @@
 			continue;
 
 		val = regcache_get_val(map, block, i);
-
-		/* Is this the hardware default?  If so skip. */
-		ret = regcache_lookup_reg(map, regtmp);
-		if (ret >= 0 && val == map->reg_defaults[ret].def)
+		if (!regcache_reg_needs_sync(map, regtmp, val))
 			continue;
 
 		map->cache_bypass = 1;
@@ -688,10 +695,7 @@
 		}
 
 		val = regcache_get_val(map, block, i);
-
-		/* Is this the hardware default?  If so skip. */
-		ret = regcache_lookup_reg(map, regtmp);
-		if (ret >= 0 && val == map->reg_defaults[ret].def) {
+		if (!regcache_reg_needs_sync(map, regtmp, val)) {
 			ret = regcache_sync_block_raw_flush(map, &data,
 							    base, regtmp);
 			if (ret != 0)