Change expected RCW offset on SD-card from 0x1000 to 0x801000

The default offset of 0x1000 (4096) bytes for RCW clashes with the GUID partition table. Luckily, LS1028A also attempts to read from a different offset according to the "QorIQ LS1028A Reference Manual":

If the Service processor detects that the RCW loading failed, it initiates RCW loading from a second RCW source. If boot fails from the RCW loaded at offset 0 or 0x1000 (in case of SD), the boot ROM searches for RCW at 8 MB (8 MB + 0x1000 for SD) offset on the device. https://www.scribd.com/document/806870300/LS1028ARM

But just copying RCW (the existing blob) to a different offset will not work as the blockcopy command embedded into BL2 has to be adjusted as well. The tool tools/nxp/create_pbl is responsible for setting it up and thus has to be patched with the changed offset of RCW on the SD-card.

Link: https://mntre.com/reform-irc-logs/2025-12-04.log.html#t13:00:19 Thanks: "Lucie L. Hartmann" lukas@mntre.com