tests: zephyr: drivers: spi: nrf54l only supports up to 8MHz SPIM

The nrf54l series SoCs only support up to 8MHz SPIM, though the
spi_controller_peripheral sets the SPIM frequency to 16MHz. This
now fails since nrfx checks if the applied frequency is valid.

Update the spi_controller_peripheral tests to set the SPIM freq to
8MHz.

Signed-off-by: Bjarki Arge Andreasen <bjarki.andreasen@nordicsemi.no>

Author: bjarki-andreasen

tests/zephyr/drivers/spi/spi_controller_peripheral/boards/nrf54ls05dk_nrf54ls05b_cpuapp.overlay

@@ -58,7 +58,7 @@
 	dut_spi_dt: test-spi-dev@0 {
 		compatible = "vnd,spi-device";
 		reg = <0>;
-		spi-max-frequency = <DT_FREQ_M(16)>;
+		spi-max-frequency = <DT_FREQ_M(8)>;
 	};
 };
 

tests/zephyr/drivers/spi/spi_controller_peripheral/boards/nrf54lv10dk_nrf54lv10a_cpuapp.overlay

@@ -65,7 +65,7 @@
 	dut_spi_dt: test-spi-dev@0 {
 		compatible = "vnd,spi-device";
 		reg = <0>;
-		spi-max-frequency = <DT_FREQ_M(16)>;
+		spi-max-frequency = <DT_FREQ_M(8)>;
 	};
 };
 

tests/zephyr/drivers/spi/spi_controller_peripheral/boards/nrf54lv10dk_nrf54lv10a_cpuapp_ns.overlay

@@ -65,7 +65,7 @@
 	dut_spi_dt: test-spi-dev@0 {
 		compatible = "vnd,spi-device";
 		reg = <0>;
-		spi-max-frequency = <DT_FREQ_M(16)>;
+		spi-max-frequency = <DT_FREQ_M(8)>;
 	};
 };