usb-pd: Apply Vconn before Vbus as per USB TypeC spec (v 1.3)
usb-pd: Apply Vconn before Vbus as per USB TypeC spec (v 1.3)

According to table 4-25 in USB TypeC spec version 1.3, Vconn should be
sourced before Vbus or within 2ms. On Grunt I am see tVconnON around 2.3
ms, which is out of spec. We can simply source Vconn first to comply with
spec.

BRANCH=none
BUG=b:72811851
TEST=Grunt's tVonnOn is now <2ms

Change-Id: I52ca6a52bf576487061b2c33f348edf58eb06ca0
Signed-off-by: Jett Rink <9d4aef0593e6843318d99df31597fb6153b89787@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/911928
Reviewed-by: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>
Reviewed-by: Edward Hill <db1406b34e091703092b6b136bdfeb2c8125fc0e@chromium.org>
Reviewed-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>

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