NET: move legacy enc28j60.c to sidetrack as enc28j60_lpc2292.c

This patch is required before the upcoming new enc28j60 driver
using SPI framework patch can be applied:
- Move legacy enc28j60.c to enc28j60_lpc2292.c.
- Change Makefile and the two affected boards' definition files.

Tested with ./MAKEALL ARM7 that both boards still compile.

Signed-off-by: Reinhard Meyer<info@emk-elektronik.de>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
diff --git a/include/configs/SMN42.h b/include/configs/SMN42.h
index adb6ac5..ba3ada1 100644
--- a/include/configs/SMN42.h
+++ b/include/configs/SMN42.h
@@ -198,6 +198,6 @@
 #define CONFIG_INITRD_TAG
 #define CONFIG_MMC			1
 /* we use this ethernet chip */
-#define CONFIG_ENC28J60
+#define CONFIG_ENC28J60_LPC2292
 
 #endif	/* __CONFIG_H */