昨晚又推送了两次代码，看commit吧，这次支持按键和LED了

主要在board.c中增加如下三个函数：

//added by mango 20150526
//wled_n GPIO35 WLAN_KN_MODE 2b01
//WDT GPIO37 WDT_MODE 1b1
void gpio_init(void)
{
    u32 val;
    printf( "MT7688 gpio init : wled and wdt\n" );
    //set gpio2_mode 1:0=2b01 wled
    val=RALINK_REG(RT2880_SYS_CNTL_BASE+0x64);
    val&=~3;
    val|=1;
    RALINK_REG(RT2880_SYS_CNTL_BASE+0x64)=val;
    //gpio44 output gpio_ctrl_1 bit3=1
    val=RALINK_REG(RT2880_REG_PIODIR+0x04);
    val|=1<<12;
    RALINK_REG(RT2880_REG_PIODIR+0x04)=val;
    //set gpio1_mode 14=1b1
    val=RALINK_REG(RT2880_SYS_CNTL_BASE+0x60);
    val|=1<<14;
    RALINK_REG(RT2880_SYS_CNTL_BASE+0x60)=val;
    //gpio38 input gpio_ctrl_1 bit5=0
    val=RALINK_REG(RT2880_REG_PIODIR+0x04);
    val&=~1<<6;
    RALINK_REG(RT2880_REG_PIODIR+0x04)=val;
}
void led_on( void )
{
    //gpio44 gpio_dclr_1 644 clear bit12
    RALINK_REG(0xb0000644)=1<<12;
}
void led_off( void )
{
    //gpio44 gpio_dset_1 634 set bit12
    RALINK_REG(0xb0000634)=1<<12;
}
int detect_wps( void )
{
    u32 val;
    val=RALINK_REG(0xb0000624);//624
    if(val&1<<6){
        return 0;
    }
    else{
        printf("wps button pressed!\n");
        return 1;
    }
}