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/tools/buildman/README b/tools/buildman/README
index 5f99a50..ce27788 100644
--- a/tools/buildman/README
+++ b/tools/buildman/README
@@ -1010,13 +1010,13 @@
     ...
     43: Convert CONFIG_SPL_USBETH_SUPPORT to Kconfig
     arm:
-    + u-boot.cfg: CONFIG_SPL_ENV_SUPPORT=1 CONFIG_SPL_NET_SUPPORT=1
+    + u-boot.cfg: CONFIG_SPL_ENV_SUPPORT=1 CONFIG_SPL_NET=1
     + u-boot-spl.cfg: CONFIG_SPL_MMC=1 CONFIG_SPL_NAND_SUPPORT=1
-    + all: CONFIG_SPL_ENV_SUPPORT=1 CONFIG_SPL_MMC=1 CONFIG_SPL_NAND_SUPPORT=1 CONFIG_SPL_NET_SUPPORT=1
+    + all: CONFIG_SPL_ENV_SUPPORT=1 CONFIG_SPL_MMC=1 CONFIG_SPL_NAND_SUPPORT=1 CONFIG_SPL_NET=1
     am335x_evm_usbspl :
-    + u-boot.cfg: CONFIG_SPL_ENV_SUPPORT=1 CONFIG_SPL_NET_SUPPORT=1
+    + u-boot.cfg: CONFIG_SPL_ENV_SUPPORT=1 CONFIG_SPL_NET=1
     + u-boot-spl.cfg: CONFIG_SPL_MMC=1 CONFIG_SPL_NAND_SUPPORT=1
-    + all: CONFIG_SPL_ENV_SUPPORT=1 CONFIG_SPL_MMC=1 CONFIG_SPL_NAND_SUPPORT=1 CONFIG_SPL_NET_SUPPORT=1
+    + all: CONFIG_SPL_ENV_SUPPORT=1 CONFIG_SPL_MMC=1 CONFIG_SPL_NAND_SUPPORT=1 CONFIG_SPL_NET=1
     44: Convert CONFIG_SPL_USB_HOST to Kconfig
     ...