wiseconnect: Get rid of PSRAM_INTERFACE_MODE

PSRAM_INTERFACE_MODE contains an hardware configuration parameter. This
parameter belongs to the DT on the Zephyr side. Hence, it can't be
defined with a macro.

Fortunately, this symbol is redundant with ...spi_config_1.inst_mode. So
we can replace the macro by this field.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>

Author: jerome-pouiller

wiseconnect/components/device/silabs/si91x/mcu/drivers/unified_api/src/sl_si91x_psram.c

@@ -1016,7 +1016,7 @@ sl_psram_return_type_t sl_si91x_psram_init()
 
   if ((psram_id.MFID == PSRAM_Device.deviceID.MFID) && (psram_id.KGD == PSRAM_Device.deviceID.KGD)) {
 
-    if (PSRAM_INTERFACE_MODE == QUAD_MODE) {
+    if (PSRAM_Device.spi_config.spi_config_1.inst_mode == QUAD_MODE) {
       /*Set the PSRAM device to QPI mode*/
       psram_enter_qpi_mode();