[nrf fromlist] tests: drivers: spi_controller_peripheral: make cpurad_dma reg bigger

This test needs more space for SPI transfer buffers.

Upstream PR: zephyrproject-rtos/zephyr#74302

Signed-off-by: Nikodem Kastelik <[email protected]>

Author: nika-nordic

tests/drivers/spi/spi_controller_peripheral/boards/nrf54h20dk_nrf54h20_cpurad.overlay

@@ -12,3 +12,11 @@
 &dut_spis {
 	memory-regions = <&cpurad_dma_region>;
 };
+
+&cpuapp_dma_region {
+	reg = <0xe80 0x80>;
+};
+
+&cpurad_dma_region {
+	reg = <0xf00 DT_SIZE_K(4)>;
+};