flapjack: usb otg power support
flapjack: usb otg power support

On flapjack, USB host VBUS is controlled by ec gpio rather than mt6370,
flapjack used pin EN_PP5000_USBC pull up to enable VBUS,used pin NCP3902_EN_L pull up to disable NCP3902.

CQ-DEPEND=CL:1446631
BUG=b:123561398
BRANCH=none
TEST=BOOTBLOCK=... make BOARD=flapjack -j flash_ec;
     1. without connect to anything, see gpio status
		0  EN_PP5000_USBC
 		0  NCP3902_EN_L
     2. with OTG device connected, see gpio status
		1*  EN_PP5000_USBC
 		1*  NCP3902_EN_L
     3. remove OTG device, see gpio status
		0*  EN_PP5000_USBC
 		0*  NCP3902_EN_L

Change-Id: Icc8ef833cc6a877620299486675a9f0fb9b85d14
Reviewed-on: https://chromium-review.googlesource.com/1384705
Commit-Ready: ChromeOS CL Exonerator Bot <fa429e5907f00867f797423aea74327bb02c91b6@appspot.gserviceaccount.com>
Tested-by: Tony Zou <e61721885f0cc9c0c50b0f4dce55c989c63eddef@huaqin.corp-partner.google.com>
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>
Reviewed-by: Tony Zou <e61721885f0cc9c0c50b0f4dce55c989c63eddef@huaqin.corp-partner.google.com>

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