cleanup: correct max port count on test
Looking at code, we only test one port, so make the test
defines match the test code
BRANCH=none
TEST=all tests pass
@@ -312,7 +312,7 @@ int ncp15wb_calculate_temp(uint16_t adc);
#endif
#if defined(TEST_USB_PRL)
-#define CONFIG_USB_PD_PORT_MAX_COUNT 2
+#define CONFIG_USB_PD_PORT_MAX_COUNT 1
#define CONFIG_USB_PD_TCPMV2
#undef CONFIG_USB_PE_SM
#undef CONFIG_USB_TYPEC_SM
