i2c: microchip-core: re-fix fake detections w/ i2cdetect

Introducing support for smbus re-broke i2cdetect, causing it to detect
devices at every i2c address, just as it did prior to being fixed in
commit 49e1f0f ("i2c: microchip-core: fix "ghost" detections").
This was caused by an oversight, where the new smbus code failed to
check the return value of mchp_corei2c_xfer(). Check it, and propagate
any errors.

Fixes: d6ceb40 ("i2c: microchip-corei2c: add smbus support")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250630-shopper-proven-500f4075e7d6@spud

Author: ConchuOD

drivers/i2c/busses/i2c-microchip-corei2c.c

@@ -435,6 +435,7 @@ static int mchp_corei2c_smbus_xfer(struct i2c_adapter *adap, u16 addr, unsigned
 	u8 tx_buf[I2C_SMBUS_BLOCK_MAX + 2];
 	u8 rx_buf[I2C_SMBUS_BLOCK_MAX + 1];
 	int num_msgs = 1;
+	int ret;
 
 	msgs[CORE_I2C_SMBUS_MSG_WR].addr = addr;
 	msgs[CORE_I2C_SMBUS_MSG_WR].flags = 0;
@@ -505,7 +506,10 @@ static int mchp_corei2c_smbus_xfer(struct i2c_adapter *adap, u16 addr, unsigned
 		return -EOPNOTSUPP;
 	}
 
-	mchp_corei2c_xfer(&idev->adapter, msgs, num_msgs);
+	ret = mchp_corei2c_xfer(&idev->adapter, msgs, num_msgs);
+	if (ret < 0)
+		return ret;
+
 	if (read_write == I2C_SMBUS_WRITE || size <= I2C_SMBUS_BYTE_DATA)
 		return 0;