imx: Support i.MX93 9X9 QSB board

Add i.MX93 9x9 Quick Start Board support.
 - Two ddr scripts included w/o inline ecc feature.
 - SDHC/NETWORK/I2C/UART supported
 - PCA9450 supported, default over drive mode
 - Documentation added.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/doc/board/nxp/index.rst b/doc/board/nxp/index.rst
index 5f1e878..734bab6 100644
--- a/doc/board/nxp/index.rst
+++ b/doc/board/nxp/index.rst
@@ -12,6 +12,7 @@
    imx8mq_evk
    imx8qxp_mek
    imx8ulp_evk
+   imx93_9x9_qsb
    imx93_11x11_evk
    imxrt1020-evk
    imxrt1050-evk