drivers: Use CONFIG_XPL_BUILD instead of CONFIG_SPL_BUILD

Use the new symbol to refer to any 'SPL' build, including TPL and VPL

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 6abcce0..3158487c 100644
--- a/drivers/usb/gadget/Makefile
+++ b/drivers/usb/gadget/Makefile
@@ -7,7 +7,7 @@
 obj-$(CONFIG_$(SPL_TPL_)USB_ETHER) += epautoconf.o config.o usbstring.o ether.o
 obj-$(CONFIG_$(SPL_TPL_)USB_ETH_RNDIS) += rndis.o
 
-ifdef CONFIG_SPL_BUILD
+ifdef CONFIG_XPL_BUILD
 obj-$(CONFIG_SPL_USB_GADGET) += g_dnl.o
 obj-$(CONFIG_SPL_DFU) += f_dfu.o
 obj-$(CONFIG_SPL_USB_SDP_SUPPORT) += f_sdp.o
@@ -21,7 +21,7 @@
 obj-$(CONFIG_USB_GADGET_DWC2_OTG) += dwc2_udc_otg.o
 obj-$(CONFIG_USB_GADGET_DWC2_OTG_PHY) += dwc2_udc_otg_phy.o
 obj-$(CONFIG_USB_GADGET_MAX3420) += max3420_udc.o
-ifndef CONFIG_SPL_BUILD
+ifndef CONFIG_XPL_BUILD
 obj-$(CONFIG_USB_GADGET_DOWNLOAD) += g_dnl.o
 obj-$(CONFIG_USB_FUNCTION_THOR) += f_thor.o
 obj-$(CONFIG_DFU_OVER_USB) += f_dfu.o