burnet: Fix SPI NSS leakage on S5
burnet: Fix SPI NSS leakage on S5

Pull low the SPI_NSS to prevent leakage on S5.

BUG=b:173647487
BRANCH=firmware-kukui-12573.B
TEST=On Burnet. No leakage on sensor SPI.

Signed-off-by: Devin Lu <052fe648504800b810f29702ef4f3db83fad68bf@quantatw.com>
Change-Id: I4f15b019dc16913e98b0cc2a0050dd6c7847afdf
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3739986
Reviewed-by: Chen-Tsung Hsieh <77554e79ae3cd4c7dffb45bb74e91a0ebfd68cd4@chromium.org>
Tested-by: Devin Lu <d4ad47e36dbc9c8af8e155263d0bf0afaae16ab2@quantatw.com>
Commit-Queue: Devin Lu <d4ad47e36dbc9c8af8e155263d0bf0afaae16ab2@quantatw.com>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec