Revert "ar71xx: use platform code for qca955x usb0 init"

This reverts commit 5b98061bb1.

As Piotr Dymacz pointed out:

In QCA MIPS based WiSOCs, for first USB interface,
device/host mode can be selected _only_ in hardware
see description of 57c641ba6e

QCA955x and QCA9563, second USB can be switched to device
mode in software (tested and confirmed on real hardware).

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

target/linux/ar71xx/patches-4.14/951-qca955x-usb0-platform.patch

@@ -1,14 +0,0 @@
---- a/arch/mips/ath79/dev-usb.c
-+++ b/arch/mips/ath79/dev-usb.c
-@@ -317,7 +317,10 @@ static void __init qca955x_usb_setup(voi
- {
- 	ath79_ehci_pdata_v2.reset_notifier = qca955x_usb_reset_notifier;
- 
--	ar9xxx_ci_usb_setup(0, ATH79_IP3_IRQ(0));
-+	ath79_usb_register("ehci-platform", 0,
-+			   QCA955X_EHCI0_BASE, QCA955X_EHCI_SIZE,
-+			   ATH79_IP3_IRQ(0),
-+			   &ath79_ehci_pdata_v2, sizeof(ath79_ehci_pdata_v2));
- 
- 	ath79_usb_register("ehci-platform", 1,
- 			   QCA955X_EHCI1_BASE, QCA955X_EHCI_SIZE,