tpm: Create a tpm_class_ops structure and use it in the drivers

This replaces the static initialization of a tpm_vendor_specific
structure in the drivers with the standard Linux idiom of providing
a const structure of function pointers.

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Reviewed-by: Joel Schopp <jschopp@linux.vnet.ibm.com>
Reviewed-by: Ashley Lai <adlai@linux.vnet.ibm.com>
[phuewe: did apply manually due to commit
191ffc6bde3 tpm/tpm_i2c_atmel: fix coccinelle warnings]
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>