ARM: dts: r8a7740: Fix W=1 dtc warnings

Warning (unit_address_vs_reg): Node /cache-controller has a reg or ranges property, but no unit name

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>