regmap: fix regcache_reg_present() for empty cache

In the initial case when no reg_defaults values are
provided and no register value was added to the cache
yet, the cache_present bitmap is NULL. If this function
is invoked for any register it should return false
(i.e. the register is not cached) instead of true.

Signed-off-by: Ionut Nicu <ioan.nicu.ext@nsn.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/base/regmap/internal.h

@@ -223,7 +223,7 @@ int regcache_set_reg_present(struct regmap *map, unsigned int reg);
 static inline bool regcache_reg_present(struct regmap *map, unsigned int reg)
 {
 	if (!map->cache_present)
-		return true;
+		return false;
 	if (reg > map->cache_present_nbits)
 		return false;
 	return map->cache_present[BIT_WORD(reg)] & BIT_MASK(reg);