arm64: dts: renesas: sparrow-hawk: Disable dtc spi_bus_bridge check

make dtbs:

    arch/arm64/boot/dts/renesas/r8a779g0.dtsi:1269.24-1283.5: Warning (spi_bus_bridge): /soc/spi@e6ea0000: incorrect #address-cells for SPI bus
      also defined at arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk.dts:471.9-486.3
    arch/arm64/boot/dts/renesas/r8a779g0.dtsi:1269.24-1283.5: Warning (spi_bus_bridge): /soc/spi@e6ea0000: incorrect #size-cells for SPI bus
      also defined at arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk.dts:471.9-486.3
    arch/arm64/boot/dts/renesas/r8a779g3-sparrow-hawk.dtb: Warning (spi_bus_reg): Failed prerequisite 'spi_bus_bridge'

The Sparrow Hawk uses the MSIOF module in I2S mode instead of SPI mode,
triggering a conflict between the SPI bus bindings and dtc:
  - Serial engines that can be SPI controllers must use "spi" as their
    node names,
  - Dtc assumes nodes named "spi" are always SPI controllers.

Fix this by disabling this specific warning for this board.

Fixes: ca764d5 ("arm64: dts: renesas: sparrow-hawk: Add MSIOF Sound support")
Reported-by: Stephen Rothwell <[email protected]>
Closes: https://lore.kernel.org/[email protected]
Suggested-by: Rob Herring <[email protected]>
Link: https://lore.kernel.org/fbad3581f297d5b95a3b2813bbae7dba25a523fd.1747039399.git.geert+renesas@glider.be
Signed-off-by: Geert Uytterhoeven <[email protected]>

Author: geertu

arch/arm64/boot/dts/renesas/Makefile

@@ -94,6 +94,7 @@ dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g2-white-hawk-single.dtb
 r8a779g2-white-hawk-single-ard-audio-da7212-dtbs := r8a779g2-white-hawk-single.dtb white-hawk-ard-audio-da7212.dtbo
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g2-white-hawk-single-ard-audio-da7212.dtb
 
+DTC_FLAGS_r8a779g3-sparrow-hawk += -Wno-spi_bus_bridge
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk.dtb
 r8a779g3-sparrow-hawk-fan-pwm-dtbs := r8a779g3-sparrow-hawk.dtb r8a779g3-sparrow-hawk-fan-pwm.dtbo
 dtb-$(CONFIG_ARCH_R8A779G0) += r8a779g3-sparrow-hawk-fan-pwm.dtb