usb: Move SPL_USB_GADGET and related Kconfig symbols to drivers/usb/

To avoid piling up all the various Kconfig symbols in one place, i.e.
common/spl/Kconfig, move the USB Kconfig symbols into drivers/usb/ .
This commit moves SPL_USB_GADGET and related symbols. Fix typo and
rename SPL_USB_GADGET to "USB Gadget Support in SPL" .

Update the gadget Makefile to match the symbol changes.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 6cfe0f3..a9edeb9 100644
--- a/drivers/usb/gadget/Makefile
+++ b/drivers/usb/gadget/Makefile
@@ -3,8 +3,8 @@
 # (C) Copyright 2000-2007
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 
-obj-$(CONFIG_USB_GADGET) += epautoconf.o config.o usbstring.o
-obj-$(CONFIG_USB_ETHER) += epautoconf.o config.o usbstring.o
+obj-$(CONFIG_$(SPL_TPL_)USB_GADGET) += epautoconf.o config.o usbstring.o
+obj-$(CONFIG_$(SPL_TPL_)USB_ETHER) += epautoconf.o config.o usbstring.o ether.o
 
 ifdef CONFIG_SPL_BUILD
 obj-$(CONFIG_SPL_USB_GADGET) += g_dnl.o
@@ -34,7 +34,6 @@
 
 obj-$(CONFIG_CI_UDC) += ci_udc.o
 
-obj-$(CONFIG_USB_ETHER) += ether.o
 obj-$(CONFIG_USB_ETH_RNDIS) += rndis.o
 
 # Devices not related to the new gadget layer depend on CONFIG_USB_DEVICE