Patch merged into coreboot/master: soc/intel/{sky, apollo}lake: Wait until GPE is clear when reading

the following patch was just integrated into master:
commit 2f3736e7aceb289d51a54679747d65eb09c1e0f1
Author: Duncan Laurie 
Date:   Thu Nov 3 10:33:43 2016 -0700

soc/intel/{sky,apollo}lake: Wait until GPE is clear when reading

When reading+clearing a GPE for use as an interrupt we need to
    re-read the status register and keep setting the clear bit until
    it actually reads back clear.  Also add a 1ms timeout in case the
    status never clears.

This is needed if a device sends a longer interrupt pulse and it
    is still asserted when the "ISR" goes to clear the status.

BUG=chrome-os-partner:59299
    TEST=test cr50 TPM with 20us pulse to ensure it can successfully
    communicate with the TPM and does not get confused due to seeing
    interrupts that it should not.

Change-Id: I384f484a1728038d3a355586146deee089b22dd9
    Signed-off-by: Duncan Laurie 
    Reviewed-on: https://review.coreboot.org/17212
    Tested-by: build bot (Jenkins)
    Reviewed-by: Furquan Shaikh 
    Reviewed-by: Paul Menzel

See https://review.coreboot.org/17212 for details.

-gerrit