regmap: Add functions to check for access on registers

We're going to be using these in quite a few places so factor out the
readable/writable/volatile/precious checks.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index a67dc68..5ab3fef 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -48,6 +48,11 @@
 	bool (*precious_reg)(struct device *dev, unsigned int reg);
 };
 
+bool regmap_writeable(struct regmap *map, unsigned int reg);
+bool regmap_readable(struct regmap *map, unsigned int reg);
+bool regmap_volatile(struct regmap *map, unsigned int reg);
+bool regmap_precious(struct regmap *map, unsigned int reg);
+
 #ifdef CONFIG_DEBUG_FS
 extern void regmap_debugfs_initcall(void);
 extern void regmap_debugfs_init(struct regmap *map);