mvebu: enable xHCI USB controller connected to PCIe

This commit fixes regression on Linksys WRT1900 (Mamba) where this device
doesn't have USB 3.0 controller integrated in SoC, instead it has Etron
EJ168 connected to PCIe lane. Previously enabled in kernel 4.4 and 4.9,
was lost in transition to 4.14.

Fixes: 4ccad92 ("mvebu: Add support for kernel 4.14")
Signed-off-by: Tomasz Maciej Nowak <[email protected]>

target/linux/mvebu/config-4.14

@@ -482,6 +482,7 @@ CONFIG_USB_STORAGE=y
 CONFIG_USB_SUPPORT=y
 CONFIG_USB_XHCI_HCD=y
 CONFIG_USB_XHCI_MVEBU=y
+CONFIG_USB_XHCI_PCI=y
 CONFIG_USB_XHCI_PLATFORM=y
 CONFIG_USE_OF=y
 CONFIG_VECTORS_BASE=0xffff0000

target/linux/mvebu/config-4.19

@@ -484,6 +484,7 @@ CONFIG_USB_STORAGE=y
 CONFIG_USB_SUPPORT=y
 CONFIG_USB_XHCI_HCD=y
 CONFIG_USB_XHCI_MVEBU=y
+CONFIG_USB_XHCI_PCI=y
 CONFIG_USB_XHCI_PLATFORM=y
 CONFIG_USE_OF=y
 CONFIG_VFP=y