spi: dt-bindings: brcm,bcm2835-spi: convert to dtschema

spi: dt-bindings: brcm,bcm2835-spi: convert to dtschema

Convert the Broadcom BCM2835 SPI0 controller to newer DT
schema. Created DT schema based on the .txt file which had
`comaptible`, `reg`, `interrupts`, `clocks` as required
properties.
Added GPL-2.0 OR BSD-2-Clause License

Signed-off-by: Kanak Shilledar <kanakshilledar111@protonmail.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://msgid.link/r/20240514070051.2959-1-kanakshilledar111@protonmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>