staging: kpc2000: kpc_i2c: Use drvdata instead of platform_data

The kpc_i2c driver stashes private state data in the platform_data
member of its device structure. In general, the platform_data structure
is used for passing data to the driver during probe() rather than as a
storage area for runtime state data. Instead, use the drvdata member
for all state info meant to be accessible in driver callbacks.

Signed-off-by: Geordan Neukum <gneukum1@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>