defconfig: arm64: Enable USB Electrical and Link test support on sm8150

Enable EHSET Test fixture driver to perform the high speed electrical
testing procedure for USB-IF compliance. Also enable the Link Layer
Test driver to allow for SuperSpeed link layer testing.

Change-Id: I46f205326b0d680bc9d885bc0121445c527c907f
Signed-off-by: Jack Pham <jackp@codeaurora.org>