arm: bcm281xx: choose 8-bit phy bus width

The Kona PHY supports an 8-bit wide UTMI interface,
therefore, choose this Kconfig setting.

Signed-off-by: Steve Rae <srae@broadcom.com>
diff --git a/configs/bcm28155_ap_defconfig b/configs/bcm28155_ap_defconfig
index 71a52a1..4c0f3b3 100644
--- a/configs/bcm28155_ap_defconfig
+++ b/configs/bcm28155_ap_defconfig
@@ -18,6 +18,7 @@
 CONFIG_USB=y
 CONFIG_USB_GADGET=y
 CONFIG_USB_GADGET_DWC2_OTG=y
+CONFIG_USB_GADGET_DWC2_OTG_PHY_BUS_WIDTH_8=y
 CONFIG_USB_GADGET_DOWNLOAD=y
 CONFIG_G_DNL_MANUFACTURER="Broadcom Corporation"
 CONFIG_G_DNL_VENDOR_NUM=0x18d1