ARM: shmobile: r8a7778 dtsi: Improve and correct HSPI nodes

ARM: shmobile: r8a7778 dtsi: Improve and correct HSPI nodes

  - Add "renesas,hspi-r8a7778" compatible value,
  - Correct reference to parent interrupt controller
    (use "interrupt-parent" instead of "interrupt-controller"),
  - Add missing "#address-cells" and "#size-cells" properties, which are
    needed when populating the SPI buses.

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Tested-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>