imx: Support i.MX91 11x11 FRDM board

Add i.MX91 11x11 FRDM Board support.
 - Four ddr scripts included w/o inline ecc feature. Support
   both 1gb and 2gb DDR
 - SDHC/EQOS/I2C/UART supported
 - PCA9451 supported, default nominal drive mode
 - Documentation added.

Signed-off-by: Joseph Guo <qijian.guo@nxp.com>

include/configs/imx91_frdm.h

@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2025 NXP
+ */
+
+#ifndef __IMX91_FRDM_H
+#define __IMX91_FRDM_H
+
+#include <linux/sizes.h>
+#include <linux/stringify.h>
+#include <asm/arch/imx-regs.h>
+
+#define CFG_SYS_UBOOT_BASE	\
+	(QSPI0_AMBA_BASE + CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR * 512)
+
+#define CFG_SYS_INIT_RAM_ADDR	0x80000000
+#define CFG_SYS_INIT_RAM_SIZE	0x200000
+
+#define CFG_SYS_SDRAM_BASE	0x80000000
+#define PHYS_SDRAM		0x80000000
+#define PHYS_SDRAM_SIZE		SZ_2G /* 2GB DDR */
+
+#define WDOG_BASE_ADDR		WDG3_BASE_ADDR
+
+#endif