drivers/i2c/tpm/cr50: Support interrupts for status

Support reading the ACPI GPE status (on x86) to determine when
the cr50 is ready to return response data or is done processing
written data.  If the interrupt is not defined by Kconfig then
it will continue to use the safe delay.

This was tested with reef hardware and a modified cr50 image
that generates interrupts at the intended points.

BUG=chrome-os-partner:53336

Change-Id: I9f78f520fd089cb4471d8826a8cfecff67398bf8
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
3 files changed