i2c: nvidia-gpu: limit reads also for combined messages

If the controller can only do 4 byte reads, this needs to be applied for
the read-part of combined messages, too.

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Fixes: c71bcdcb ("i2c: add i2c bus driver for NVIDIA GPU")
Acked-by: Ajay Gupta <ajayg@nvidia.com>
Tested-by: Ajay Gupta <ajayg@nvidia.com>