regmap: fix the kerneldoc for regmap_test_bits()

The kerneldoc comment for regmap_test_bits() says that it returns -1 on
regmap_read() failure. This is not true - it will propagate the error
code returned by regmap_read(). Fix it.

Fixes: aa2ff9db ("regmap: provide helpers for simple bit operations")
Signed-off-by: NBartosz Golaszewski <bgolaszewski@baylibre.com>
Link: https://lore.kernel.org/r/20200607093421.22209-1-brgl@bgdev.plSigned-off-by: NMark Brown <broonie@kernel.org>

drivers/base/regmap/regmap.c

@@ -2936,8 +2936,9 @@ EXPORT_SYMBOL_GPL(regmap_update_bits_base);
  * @reg: Register to read from
  * @bits: Bits to test
  *
- * Returns -1 if the underlying regmap_read() fails, 0 if at least one of the
- * tested bits is not set and 1 if all tested bits are set.
+ * Returns 0 if at least one of the tested bits is not set, 1 if all tested
+ * bits are set and a negative error number if the underlying regmap_read()
+ * fails.
  */
 int regmap_test_bits(struct regmap *map, unsigned int reg, unsigned int bits)
 {