regulator: stm32-vrefbuf: fix check on ready flag

stm32_vrefbuf_enable() wrongly checks VRR bit: 0 stands for not ready,
1 for ready. It currently checks the opposite.
This makes enable routine to exit immediately without waiting for ready
flag.

Fixes: 0cdbf481e927 ("regulator: Add support for stm32-vrefbuf")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org

drivers/regulator/stm32-vrefbuf.c

@@ -51,7 +51,7 @@ static int stm32_vrefbuf_enable(struct regulator_dev *rdev)
 	 * arbitrary timeout.
 	 */
 	ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val,
-				 !(val & STM32_VRR), 650, 10000);
+				 val & STM32_VRR, 650, 10000);
 	if (ret) {
 		dev_err(&rdev->dev, "stm32 vrefbuf timed out!\n");
 		val = readl_relaxed(priv->base + STM32_VREFBUF_CSR);