sifive: fu540: Enable spi-nor flash support

HiFive Unleashed A00 support is25wp256 spi-nor flash,
So enable the same and add test result log for future
reference.

Tested on SiFive FU540 board.

Thanks to Sagar for various use cases and tests.

[QUAD mode in dt with spi-tx-bus-width: <4>]
 pp opcode      = 0x34 [QUAD MODE]
 read opcode  = 0x6c  [QUAD MODE]
 erase opcode = 0x21

SPI-NOR:
1. erase entire flash: Pass
2. write entire flash: Pass
3. read entire flash: Pass
4. cmp 32MiB read back data: Pass
5. MMC: Booted Linux and dtb from mmc

[SPI MODE in dt with spi-tx-bus-width: <1>]
pp opcode     = 0x12 [SPI MODE]
read opcode  = 0xc   [SPI MODE]
erase opcode = 0x21

SPI-NOR:
1. erase entire flash: Pass
2. write entire flash: Pass
3. read entire flash: Pass
4. cmp 32MiB read back data: Pass
5. MMC: Booted Linux and dtb from mmc

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Sagar Kadam <sagar.kadam@sifive.com>
diff --git a/arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi b/arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi
index 8a784b5..2aebfab 100644
--- a/arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi
+++ b/arch/riscv/dts/hifive-unleashed-a00-u-boot.dtsi
@@ -5,6 +5,7 @@
 
 / {
 	aliases {
+		spi0 = &qspi0;
 		spi2 = &qspi2;
 	};
 };
diff --git a/board/sifive/fu540/Kconfig b/board/sifive/fu540/Kconfig
index 5ca2147..75661f3 100644
--- a/board/sifive/fu540/Kconfig
+++ b/board/sifive/fu540/Kconfig
@@ -26,6 +26,7 @@
 	imply CMD_FS_GENERIC
 	imply CMD_NET
 	imply CMD_PING
+	imply CMD_SF
 	imply CLK_SIFIVE
 	imply CLK_SIFIVE_FU540_PRCI
 	imply DOS_PARTITION
@@ -40,6 +41,8 @@
 	imply SIFIVE_SERIAL
 	imply SPI
 	imply SPI_SIFIVE
+	imply SPI_FLASH
+	imply SPI_FLASH_ISSI
 	imply MMC
 	imply MMC_SPI
 	imply MMC_BROKEN_CD