global: Migrate CONFIG_SH_ETHER_CACHE_WRITEBACK to CFG

Perform a simple rename of CONFIG_SH_ETHER_CACHE_WRITEBACK to CFG_SH_ETHER_CACHE_WRITEBACK

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/include/configs/porter.h b/include/configs/porter.h
index 143e9a4..f217141 100644
--- a/include/configs/porter.h
+++ b/include/configs/porter.h
@@ -25,7 +25,7 @@
 #define CONFIG_SH_ETHER_USE_PORT	0
 #define CONFIG_SH_ETHER_PHY_ADDR	0x1
 #define CONFIG_SH_ETHER_PHY_MODE PHY_INTERFACE_MODE_RMII
-#define CONFIG_SH_ETHER_CACHE_WRITEBACK
+#define CFG_SH_ETHER_CACHE_WRITEBACK
 #define CFG_SH_ETHER_CACHE_INVALIDATE
 #define CFG_SH_ETHER_ALIGNE_SIZE	64