rt1718s: ignore cached source flag for enable sourcing
rt1718s: ignore cached source flag for enable sourcing

When FRS happens (failed or succeed), the cached source flag
may not reflect the correct status immediately. So,
ignore the source flag to update the VBUS charge supplier and enable
source control.

BUG=b:234352018
TEST=unplug FRS hub with adapter connected, and the VBUS supplier
     disappeared.
BRANCH=cherry

Change-Id: Ia735efb3ea15733be01990613ab256d8e73a7f4a
Signed-off-by: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3747170
Auto-Submit: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@google.com>
Commit-Queue: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>
Tested-by: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@google.com>
Reviewed-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>

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