net: Rename SPL_NET_SUPPORT to SPL_NET

Rename this option so that CONFIG_IS_ENABLED can be used with it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/chromebook_samus_tpl_defconfig b/configs/chromebook_samus_tpl_defconfig
index d97c305..b231b3b 100644
--- a/configs/chromebook_samus_tpl_defconfig
+++ b/configs/chromebook_samus_tpl_defconfig
@@ -34,7 +34,7 @@
 CONFIG_HANDOFF=y
 CONFIG_SPL_SEPARATE_BSS=y
 CONFIG_SPL_DM_SPI_FLASH=y
-CONFIG_SPL_NET_SUPPORT=y
+CONFIG_SPL_NET=y
 CONFIG_SPL_PCI=y
 CONFIG_SPL_PCH=y
 CONFIG_TPL_PCI=y