Support both RMS and Max Linearity Validation

We have a spec for both Max and RMS linearity errors, but previously
this test only actually checked the maximum error.  This worked well
enough, but for completeness, it should report and compute both of
the values.  To do this, this CL adds a parameter when we instantiate
a LinearityValidator object to say if it should validate the RMS error
or the Max error.

BUG=chromium:586298
TEST=ran through the tests by hand and the values seem correct, and
the generated report looks good.

Change-Id: I1fb90cb3e410b9e23366256831c30514953d37ed
Signed-off-by: Charlie Mooney <charliemooney@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/327329
Reviewed-by: Shyh-In Hwang <josephsih@chromium.org>
2 files changed