spi: dt-bindings: qcom,spi-qcom-qspi: Add qcom,qcs615-qspi compatible

spi: dt-bindings: qcom,spi-qcom-qspi: Add qcom,qcs615-qspi compatible

Add support for the QSPI controller on QCS615 SoC.

Move allOf section after required properties and add if:then constraint
to require minimum 2 interconnects for qcs615 variant.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com>
Link: https://patch.msgid.link/20260429-spi-nor-v5-1-993016c9711e@oss.qualcomm.com
Signed-off-by: Mark Brown <broonie@kernel.org>