drm/imx: Kconfig: Remove duplicated 'select DRM_KMS_HELPER' line

A duplicated line 'select DRM_KMS_HELPER' was introduced in Kconfig file
by commit 09717af7 ("drm: Remove CONFIG_DRM_KMS_CMA_HELPER option"),
so remove it.

Fixes: 09717af7 ("drm: Remove CONFIG_DRM_KMS_CMA_HELPER option")
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20221009023527.3669647-1-victor.liu@nxp.com

drivers/gpu/drm/imx/Kconfig

@@ -4,7 +4,6 @@ config DRM_IMX
 	select DRM_KMS_HELPER
 	select VIDEOMODE_HELPERS
 	select DRM_GEM_DMA_HELPER
-	select DRM_KMS_HELPER
 	depends on DRM && (ARCH_MXC || ARCH_MULTIPLATFORM || COMPILE_TEST)
 	depends on IMX_IPUV3_CORE
 	help