Convert CONFIG_USB_EHCI_IS_TDI to Kconfig

On mvebu this is defined if and only if !ARM64.

Otherwise it is defined for boards with ARCH_MX23, ARCH_TEGRA and
ARCH_ZYNQ, and also for SOC_AR934X (tplink_wdr4300).

Signed-off-by: Marek BehĂșn <marek.behun@nic.cz>
diff --git a/arch/mips/mach-ath79/Kconfig b/arch/mips/mach-ath79/Kconfig
index bdb23b5..cd85d1b 100644
--- a/arch/mips/mach-ath79/Kconfig
+++ b/arch/mips/mach-ath79/Kconfig
@@ -20,6 +20,7 @@
 	select SUPPORTS_BIG_ENDIAN
 	select SUPPORTS_CPU_MIPS32_R1
 	select SUPPORTS_CPU_MIPS32_R2
+	select USB_EHCI_IS_TDI if USB_EHCI_HCD
 	help
 	  This supports QCA/Atheros ar934x family SOCs.