tpm: rename chip->dev to chip->pdev

Rename chip->dev to chip->pdev to make it explicit that this not the
character device but actually represents the platform device.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jasob Gunthorpe <jason.gunthorpe@obsidianresearch.com>
Reviewed-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Peter Huewe <peterhuewe@gmx.de>
Tested-by: Scot Doyle <lkml14@scotdoyle.com>
Tested-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>