net: Move network rules to drivers/net

The code under drivers/net is related to ethernet networking drivers, in
some fashion or another.  Drop these from the top-level Makefile and
also move the phy rule into drivers/net/Makefile which is where it
belongs.  Make the new rule for drivers/net check for the build-stage
relevant ETH symbol.

Fix up some Kconfig dependencies while we're here to mirror how the
Makefile logic now works.

Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Introduce ETH, Kconfig dependency changes, am43xx fix]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/Makefile b/drivers/Makefile
index 1283b88..4cbc407 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -18,6 +18,7 @@
 obj-$(CONFIG_$(SPL_TPL_)MMC) += mmc/
 obj-y += mtd/
 obj-$(CONFIG_$(SPL_)MULTIPLEXER) += mux/
+obj-$(CONFIG_$(SPL_TPL_)ETH) += net/
 obj-$(CONFIG_$(SPL_TPL_)PCH) += pch/
 obj-$(CONFIG_$(SPL_TPL_)PCI) += pci/
 obj-$(CONFIG_$(SPL_TPL_)PHY) += phy/
@@ -48,9 +49,6 @@
 obj-$(CONFIG_ARCH_IMX8M) += ddr/imx/imx8m/
 obj-$(CONFIG_IMX8ULP_DRAM) += ddr/imx/imx8ulp/
 obj-$(CONFIG_SPL_DM_RESET) += reset/
-obj-$(CONFIG_SPL_ETH) += net/
-obj-$(CONFIG_SPL_ETH) += net/phy/
-obj-$(CONFIG_SPL_USB_ETHER) += net/phy/
 obj-$(CONFIG_SPL_MUSB_NEW) += usb/musb-new/
 obj-$(CONFIG_SPL_USB_GADGET) += usb/gadget/
 obj-$(CONFIG_SPL_USB_GADGET) += usb/common/