ARM: dts: gemini: NAS4220-B: fis-index-block with 128 KiB sectors

Steven Maddox reported in the OpenWrt bugzilla, that his
RaidSonic IB-NAS4220-B was no longer booting with the new
OpenWrt 21.02 (uses linux 5.10's device-tree). However, it was
working with the previous OpenWrt 19.07 series (uses 4.14).

|[ 5.548038] No RedBoot partition table detected in 30000000.flash
|[ 5.618553] Searching for RedBoot partition table in 30000000.flash at offset 0x0
|[ 5.739093] No RedBoot partition table detected in 30000000.flash
|...
|[ 7.039504] Waiting for root device /dev/mtdblock3...

The provided bootlog shows that the RedBoot partition parser was
looking for the partition table "at offset 0x0". Which is strange
since the comment in the device-tree says it should be at 0xfe0000.

Further digging on the internet led to a review site that took
some useful PCB pictures of their review unit back in February 2009.
Their picture shows a Spansion S29GL128N11TFI01 flash chip.

>From Spansion's Datasheet:
"S29GL128N: One hundred twenty-eight 64 Kword (128 Kbyte) sectors"
Steven also provided a "cat /sys/class/mtd/mtd0/erasesize" from his
unit: "131072".

With the 128 KiB Sector/Erasesize in mind. This patch changes the
fis-index-block property to (0xfe0000 / 0x20000) = 0x7f.

Fixes: b5a923f8c739 ("ARM: dts: gemini: Switch to redboot partition parsing")
Reported-by: Steven Maddox <[e-mail]>
Signed-off-by: Christian Lamparter <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
Tested-by: Steven Maddox <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]'
Bugzilla: https://bugs.openwrt.org/index.php?do=details&task_id=4137
Signed-off-by: Arnd Bergmann <[e-mail]>

arch/arm/boot/dts/gemini-nas4220b.dts

···
 			partitions {
 				compatible = "redboot-fis";
 				/* Eraseblock at 0xfe0000 */
-				fis-index-block = <0x1fc>;
+				fis-index-block = <0x7f>;
 			};
 		};