dt-bindings: fuse: Document R-Car E-FUSE / PFC

Document support for E-FUSE non-volatile memory accessible through PFC
on R-Car V3U and S4-8.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/03e43e97941df238ef1a618852aecd7be68adbb0.1716974502.git.geert+renesas@glider.be