configs: imxrt1020-evk: enable imx gpt timer as tick-timer

Let's enable imx-gpt-timer in imx1020-evk defconfig.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
diff --git a/configs/imxrt1020-evk_defconfig b/configs/imxrt1020-evk_defconfig
index ad408eb..f0b05b7 100644
--- a/configs/imxrt1020-evk_defconfig
+++ b/configs/imxrt1020-evk_defconfig
@@ -61,6 +61,7 @@
 CONFIG_FSL_LPUART=y
 CONFIG_TIMER=y
 CONFIG_SPL_TIMER=y
+CONFIG_IMX_GPT_TIMER=y
 CONFIG_SHA1=y
 CONFIG_SHA256=y
 CONFIG_HEXDUMP=y