pd: wait to send source cap until port partner is showing UFP
pd: wait to send source cap until port partner is showing UFP

Wait to send source cap packet until port partner is showing
UFP on CC line. This is necessary because while we are applying
VBUS, the other side could toggle its role, and when VBUS is
finally up, we must wait to send source cap until other side
is pulling down.

BUG=none
BRANCH=samus
TEST=make buildall

Change-Id: If7e811913f5ec9eed28171ffca0cec98712b96fe
Signed-off-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/227722
Reviewed-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>
Reviewed-by: Todd Broch <035f5b1f817cbb94019cec357b99778115602b63@chromium.org>

fourier49/BZ_DEV_EC,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,eatbyte/chromium-ec,fourier49/BIZ_EC,md5555/ec,eatbyte/chromium-ec,akappy7/ChromeOS_EC_LED_Diagnostics,fourier49/BIZ_EC,mtk09422/chromiumos-platform-ec,coreboot/chrome-ec,fourier49/BZ_DEV_EC,longsleep/ec,mtk09422/chromiumos-platform-ec,md5555/ec,coreboot/chrome-ec,eatbyte/chromium-ec,longsleep/ec,longsleep/ec,coreboot/chrome-ec,fourier49/BIZ_EC,coreboot/chrome-ec,md5555/ec,fourier49/BZ_DEV_EC,fourier49/BIZ_EC,eatbyte/chromium-ec,mtk09422/chromiumos-platform-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,longsleep/ec,fourier49/BZ_DEV_EC,mtk09422/chromiumos-platform-ec,md5555/ec