tpm: replace tpm_gen_interrupt() with tpm_tis_gen_interrupt()

Since tpm_gen_interrupt() is only used in tpm_tis_core.c this commit
replaces it with an internal tpm_tis_gen_interrupt(). The semantics
also changed in a way that on a system error the driver initialization
is failed.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>