[i2c] Two start conditions for PCA9554

[Hans J. Koch]

I have an embedded board with a PCA9554 on it. It's an 8-bit IO expander
similar to the PCF8574 in mainline. One difference is that when reading
from the inputs, you have to do the following:

- start condition
- send slave address, R/W=0
- send command (0x00 = read input register)
- issue another start condition (!)
- send slave address, R/W=1
- read data
- stop condition

Can such a protocol be handled by the i2c subsystem?

Thanks,
Hans