configs: starfive: fix tftpboot file waite a long time for the first time
ARP_TIMEOUT is too large, then will waite a long time for the first time
Set ARP_TIMEOUT to 500 refer to others
Set PHY_ANEG_TIMEOUT needs longer aneg time for the 2nd phy
Signed-off-by: Jianlong Huang <jianlong.huang@starfivetech.com>