SOCFPGA: remove CONFIG_AUTONEG_TIMEOUT

This macro is defined, but not referenced by anyone.

I did not touch config_whitelist.txt - the CONFIG will be dropped
by the next re-sync.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

include/configs/socfpga_common.h

@@ -94,7 +94,6 @@
 #if defined(CONFIG_CMD_NET) && !defined(CONFIG_SOCFPGA_VIRTUAL_TARGET)
 #define CONFIG_DW_ALTDESCRIPTOR
 #define CONFIG_MII
-#define CONFIG_AUTONEG_TIMEOUT		(15 * CONFIG_SYS_HZ)
 #endif
 
 /*