fusb302: Don't flush RX FIFO on GoodCRC
fusb302: Don't flush RX FIFO on GoodCRC

Depending on timing, additional important messages may reside on our RX
FIFO at the time we process GoodCRC. Therefore, rather than flushing the
RX FIFO, simply read and discard the GoodCRC message.

BUG=chrome-os-partner:314492
BRANCH=None
TEST=Manual on Snoball with subsequent PWM changes. Verify PD contact
can be established with samus.

Signed-off-by: Shawn Nematbakhsh <5259333ce42e3ace6a73988cec7115ed9d3a661a@chromium.org>
Change-Id: I4f4fab1bc318d1bce1effffad9a792c5b4a43761
Reviewed-on: https://chromium-review.googlesource.com/314871
Commit-Ready: Shawn N <5259333ce42e3ace6a73988cec7115ed9d3a661a@chromium.org>
Tested-by: Shawn N <5259333ce42e3ace6a73988cec7115ed9d3a661a@chromium.org>
Reviewed-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>

akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics