zephyr: Add tests for bmi160_sec_raw_{read|write}8()
zephyr: Add tests for bmi160_sec_raw_{read|write}8()

Add tests for the secondary i2c bus read/write functions. These are for
accessing a separate magnetometer chip through the BMI160 in a sort of
proxy/passthrough configuration.

BRANCH=None
BUG=b:184856157
TEST=zmake -D configure --test test-drivers

Signed-off-by: Tristan Honscheid <1e17951ff5ffc8afe254954c03de64afef62fe52@google.com>
Change-Id: I637c4aab571aeaa80ace24596d65838bfd51b658
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3262102
Reviewed-by: Keith Short <f6d578f97033c25f1206cb57d52f358974c82954@chromium.org>

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