usb: Correct CLEAR_FEATURE code in ehci-hcd

This commit broke USB2 on link (Chromebook Pixel):

  020bbcb usb: hub: Power-cycle on root-hub ports

However the root cause seems to be a missing mask and missing 'break'
in ehci-hcd.c. This patch fixes both.

On link, 'usb start' with a USB keyboard and memory stick inserted now
finds both. The keyboard works as expected. Also ext2ls shows a directory
listing from the memory stick.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/usb/host/ehci-hcd.c

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index e0f3e4b..445759b 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -809,21 +809,23 @@
 		break;
 	case USB_REQ_CLEAR_FEATURE | ((USB_DIR_OUT | USB_RT_PORT) << 8):
 		reg = ehci_readl(status_reg);
+		reg &= ~EHCI_PS_CLEAR;
 		switch (le16_to_cpu(req->value)) {
 		case USB_PORT_FEAT_ENABLE:
 			reg &= ~EHCI_PS_PE;
 			break;
 		case USB_PORT_FEAT_C_ENABLE:
-			reg = (reg & ~EHCI_PS_CLEAR) | EHCI_PS_PE;
+			reg |= EHCI_PS_PE;
 			break;
 		case USB_PORT_FEAT_POWER:
 			if (HCS_PPC(ehci_readl(&ctrl->hccr->cr_hcsparams)))
-				reg = reg & ~(EHCI_PS_CLEAR | EHCI_PS_PP);
+				reg &= ~EHCI_PS_PP;
+			break;
 		case USB_PORT_FEAT_C_CONNECTION:
-			reg = (reg & ~EHCI_PS_CLEAR) | EHCI_PS_CSC;
+			reg |= EHCI_PS_CSC;
 			break;
 		case USB_PORT_FEAT_OVER_CURRENT:
-			reg = (reg & ~EHCI_PS_CLEAR) | EHCI_PS_OCC;
+			reg |= EHCI_PS_OCC;
 			break;
 		case USB_PORT_FEAT_C_RESET:
 			ctrl->portreset &= ~(1 << port);