[nrf fromlist] tests: drivers: mspi: api: make test generic

Add definition of MSPI_PORT for other platforms to make the test
generic.

Upstream PR #: 92790

Signed-off-by: Magdalena Pastula <magdalena.pastula@nordicsemi.no>

Author: magp-nordic

tests/drivers/mspi/api/src/main.c

@@ -23,6 +23,8 @@ typedef enum mspi_timing_param mspi_timing_param;
 typedef struct mspi_ambiq_timing_cfg mspi_timing_cfg;
 typedef enum mspi_ambiq_timing_param mspi_timing_param;
 #define MSPI_PORT ((DT_REG_ADDR(MSPI_BUS_NODE) - MSPI0_BASE) / (MSPI1_BASE - MSPI0_BASE))
+#else
+#define MSPI_PORT 0
 #endif
 
 static const struct device *mspi_devices[] = {