fix(llcc68): move SPI CS delay to devicetree

Zephyr deprecates passing the chip-select delay as the variadic delay argument to SPI_DT_SPEC_INST_GET. Remove that deprecated macro argument from the raw LLCC68 device initializer.

Add spi-cs-setup-delay-ns and spi-cs-hold-delay-ns defaults to the custom LLCC68 devicetree binding. Both defaults are 100000 ns, preserving the previous 100 us delay behavior while using the current Zephyr SPI devicetree properties.

Verified with cmake -S . -B build and cmake --build build from the parent application.

dts/bindings/semtech,llcc68-weihua.yaml

@@ -47,3 +47,9 @@ properties:
     description: |
       Antenna switch RX enable GPIO. If set, the driver tracks the
       state of the radio and controls the RF switch.
+
+  spi-cs-setup-delay-ns:
+    default: 100000
+
+  spi-cs-hold-delay-ns:
+    default: 100000