imx93_evk: add back Low drive mode ddr timing file

Add back low drive mode 1866mts ddr timing file, no need
CONFIG_IMX9_LOW_DRIVE_MODE anymore, using runtime selection.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/board/freescale/imx93_evk/Makefile b/board/freescale/imx93_evk/Makefile
index 575f8e9..ede8d20 100644
--- a/board/freescale/imx93_evk/Makefile
+++ b/board/freescale/imx93_evk/Makefile
@@ -8,5 +8,5 @@
 
 ifdef CONFIG_SPL_BUILD
 obj-y += spl.o
-obj-$(CONFIG_IMX93_EVK_LPDDR4X) += lpddr4x_timing.o
+obj-$(CONFIG_IMX93_EVK_LPDDR4X) += lpddr4x_timing.o lpddr4x_timing_1866mts.o
 endif