[bsp][imxrt1060] application: fix undeclared identifier error

Fix below build error when using LVGL:

applications/lvgl/lv_port_indev.c(73): error: use of undeclared
identifier 'BOARD_Touch_I2C_Send'
    .I2C_SendFunc     = BOARD_Touch_I2C_Send,
                        ^
applications/lvgl/lv_port_indev.c(74): error: use of undeclared
identifier 'BOARD_Touch_I2C_Receive'
    .I2C_ReceiveFunc  = BOARD_Touch_I2C_Receive,
                        ^
applications/lvgl/lv_port_indev.c(154): warning: implicit declaration of
function 'BOARD_LPI2C_Init' is invalid in C99
[-Wimplicit-function-declaration]
    BOARD_LPI2C_Init(TOUCH_I2C, TOUCH_I2C_CLOCK_FREQ);
    ^

Signed-off-by: Ting Liu <ting.liu@nxp.com>

bsp/imxrt/imxrt1060-nxp-evk/applications/lvgl/lv_port_indev.c

@@ -16,6 +16,7 @@
 #include "lvgl.h"
 
 #include "board.h"
+#include "touchpad.h"
 #include "fsl_video_common.h"
 #include "fsl_lpi2c.h"
 #include "fsl_gpio.h"