regmap: cache: Fix num_reg_defaults computation from reg_defaults_raw

In 3245d460 (regmap: cache: Fall back to register by register read for
cache defaults) non-readable registers are skipped when initializing
reg_defaults, but are still included in num_reg_defaults. So there can
be uninitialized entries at the end of reg_defaults, which can cause
problems when the register cache initializes from the full array.

Fixed it by excluding non-readable registers from the count as well.
Signed-off-by: Maarten ter Huurne <maarten@treewalker.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regcache.c

@@ -38,10 +38,11 @@ static int regcache_hw_init(struct regmap *map)
 
 	/* calculate the size of reg_defaults */
 	for (count = 0, i = 0; i < map->num_reg_defaults_raw; i++)
-		if (!regmap_volatile(map, i * map->reg_stride))
+		if (regmap_readable(map, i * map->reg_stride) &&
+		    !regmap_volatile(map, i * map->reg_stride))
 			count++;
 
-	/* all registers are volatile, so just bypass */
+	/* all registers are unreadable or volatile, so just bypass */
 	if (!count) {
 		map->cache_bypass = true;
 		return 0;