tests: adc: Add support for lpcxpresso55s28 in the ADC test

Add lpcxpresso55s28 board to the ADC test to prevent compilation issues.

Signed-off-by: Christian Taedcke <[email protected]>

Author: chrta

tests/drivers/adc/adc_api/src/test_adc.c

@@ -223,7 +223,8 @@
 #define ADC_1ST_CHANNEL_ID	4
 #define ADC_2ND_CHANNEL_ID	5
 
-#elif defined(CONFIG_BOARD_LPCXPRESSO55S69_CPU0)
+#elif defined(CONFIG_BOARD_LPCXPRESSO55S69_CPU0) || \
+	defined(CONFIG_BOARD_LPCXPRESSO55S28)
 #define ADC_DEVICE_NAME		DT_LABEL(DT_INST(0, nxp_lpc_lpadc))
 #define ADC_RESOLUTION		12
 #define ADC_GAIN		ADC_GAIN_1