pbio/drv/clock: Add none driver.

This doesn't work with the static inlines, so make a placeholder driver for new ports that don't have a clock yet.

Author: laurensvalk

bricks/_common/sources.mk

@@ -138,6 +138,7 @@ PBIO_SRC_C = $(addprefix lib/pbio/,\
 	drv/charger/charger_mp2639a.c \
 	drv/clock/clock_ev3rt.c \
 	drv/clock/clock_linux.c \
+	drv/clock/clock_none.c \
 	drv/clock/clock_nxt.c \
 	drv/clock/clock_stm32.c \
 	drv/clock/clock_test.c \

lib/pbio/drv/clock/clock_none.c

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2024 The Pybricks Authors
+
+#include <pbdrv/config.h>
+
+#if PBDRV_CONFIG_CLOCK_NONE
+
+#include <stdint.h>
+
+void pbdrv_clock_init(void) {
+}
+
+uint32_t pbdrv_clock_get_us(void) {
+    return 0;
+}
+
+uint32_t pbdrv_clock_get_ms(void) {
+    return 0;
+}
+
+uint32_t pbdrv_clock_get_100us(void) {
+    return 0;
+}
+
+#endif // PBDRV_CONFIG_CLOCK_NONE