i2c: st: Fix return in case of arbitration lost

This patch fixes the error returned to the i2c_transfer function
to -EAGAIN in case of arbitratin lost, so that the retry mechanism
can be used.
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-st.c

@@ -574,7 +574,7 @@ static irqreturn_t st_i2c_isr_thread(int irq, void *data)
 		writel_relaxed(it, i2c_dev->base + SSC_IEN);
 
 		st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
-		c->result = -EIO;
+		c->result = -EAGAIN;
 		break;
 
 	default: