i2c: algo: bit: add flag to whitelist atomic transfers

Use the new xfer_atomic callback to check a newly introduced flag to
whitelist atomic transfers. This will report configurations which
worked accidently.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

include/linux/i2c-algo-bit.h

@@ -33,6 +33,7 @@ struct i2c_algo_bit_data {
 				   minimum 5 us for standard-mode I2C and SMBus,
 				   maximum 50 us for SMBus */
 	int timeout;		/* in jiffies */
+	bool can_do_atomic;	/* callbacks don't sleep, we can be atomic */
 };
 
 int i2c_bit_add_bus(struct i2c_adapter *);