mtd: probe SPI NOR devices in mtd_probe_devices()

In order for `mtd list` U-Boot command to list SPI NOR devices without
the need to run `sf probe` before, we have to probe SPI NOR devices in
mtd_probe_devices().

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Cc: Priyanka Jain <priyanka.jain@nxp.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Heiko Schocher <hs@denx.de>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/drivers/mtd/mtd_uboot.c b/drivers/mtd/mtd_uboot.c
index a652d43..90767ec 100644
--- a/drivers/mtd/mtd_uboot.c
+++ b/drivers/mtd/mtd_uboot.c
@@ -115,6 +115,18 @@
 static void mtd_probe_uclass_mtd_devs(void) { }
 #endif
 
+#if IS_ENABLED(CONFIG_DM_SPI_FLASH) && IS_ENABLED(CONFIG_SPI_FLASH_MTD)
+static void mtd_probe_uclass_spi_nor_devs(void)
+{
+	struct udevice *dev;
+
+	uclass_foreach_dev_probe(UCLASS_SPI_FLASH, dev)
+		;
+}
+#else
+static void mtd_probe_uclass_spi_nor_devs(void) { }
+#endif
+
 #if defined(CONFIG_MTD_PARTITIONS)
 
 #define MTDPARTS_MAXLEN         512
@@ -310,6 +322,7 @@
 	struct mtd_info *mtd;
 
 	mtd_probe_uclass_mtd_devs();
+	mtd_probe_uclass_spi_nor_devs();
 
 	/*
 	 * Check if mtdparts/mtdids changed, if the MTD dev list was updated
@@ -370,6 +383,7 @@
 int mtd_probe_devices(void)
 {
 	mtd_probe_uclass_mtd_devs();
+	mtd_probe_uclass_spi_nor_devs();
 
 	return 0;
 }