arm64: dts: renesas: sparrow-hawk: Describe generic SPI NOR support

arm64: dts: renesas: sparrow-hawk: Describe generic SPI NOR support

Retronix R-Car V4H Sparrow Hawk EVTA1 is populated with Spansion
S25FS512S, EVTB1 is populated with Winbond W77Q51NW.  Describe the SPI
NOR using the generic "jedec,spi-nor" compatible, because both FLASHes
can be auto-detected based on their built-in IDs.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250806150048.9364-1-marek.vasut+renesas@mailbox.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>