[PATCH] docs/platform: sifive_fu540: Update U-Boot defconfig name

[Bin Meng]

With latest U-Boot upstream (v2021.07 in development), the defconfig
name has been changed to sifive_unleashed_defconfig. Update the doc.

Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
---

 docs/platform/sifive_fu540.md | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/docs/platform/sifive_fu540.md b/docs/platform/sifive_fu540.md
index b4d3c60..b38df47 100644
--- a/docs/platform/sifive_fu540.md
+++ b/docs/platform/sifive_fu540.md
@@ -42,7 +42,7 @@ make PLATFORM=sifive/fu540 FW_PAYLOAD_PATH=<linux_build_directory>/arch/riscv/bo
 
 The command-line example here assumes that U-Boot was compiled using the
 sifive_fu540_defconfig configuration and with U-Boot v2020.01, and up to
-v2020.07-rc3.
+v2021.04. sifive_unleashed_defconfig shall be used with v2021.07 or above.
 
 ```
 make PLATFORM=sifive/fu540 FW_PAYLOAD_PATH=<u-boot_build_dir>/u-boot-dtb.bin
@@ -153,11 +153,12 @@ This is because QEMU generates a device tree blob on the fly based on the
 command line parameters and it's compatible with the one used in the upstream
 Linux kernel.
 
-When U-Boot v2020.01 (or higher) is used as the payload, as the SiFive FU540
+When U-Boot v2021.07 (or higher) is used as the payload, as the SiFive FU540
 DTB for the real hardware is embedded in U-Boot binary itself, due to the same
-reason above, we need to switch the U-Boot sifive_fu540_defconfig configuration
-from **CONFIG_OF_SEPARATE** to **CONFIG_OF_PRIOR_STAGE** so that U-Boot uses the
-DTB generated by QEMU, and u-boot.bin should be used as the payload image, like:
+reason above, we need to switch the U-Boot sifive_unleashed_defconfig
+configuration from **CONFIG_OF_SEPARATE** to **CONFIG_OF_PRIOR_STAGE** so that
+U-Boot uses the DTB generated by QEMU, and u-boot.bin should be used as the
+payload image, like:
 
 ```
 make PLATFORM=sifive/fu540 FW_PAYLOAD_PATH=<u-boot_build_dir>/u-boot.bin
-- 
2.25.1