Bunch of small fixes (#154)

* use valid_params_if macro for lock assertion

* fixup param checking in pwm.h

* Fix range of fractional divider parameter check in pwm.h

Co-authored-by: Luke Wren <wren6991@gmail.com>

src/common/pico_sync/include/pico/lock_core.h

@@ -10,6 +10,11 @@
 #include "pico.h"
 #include "hardware/sync.h"
 
+// PICO_CONFIG: PARAM_ASSERTIONS_ENABLED_LOCK_CORE, Enable/disable assertions in the lock core, type=bool, default=1, group=pico_sync
+#ifndef PARAM_ASSERTIONS_ENABLED_LOCK_CORE
+#define PARAM_ASSERTIONS_ENABLED_LOCK_CORE 1
+#endif
+
 /** \file lock_core.h
  *  \ingroup pico_sync
  *

src/common/pico_sync/lock_core.c

@@ -7,7 +7,7 @@
 #include "pico/lock_core.h"
 
 void lock_init(lock_core_t *core, uint lock_num) {
-    assert(lock_num < NUM_SPIN_LOCKS);
+    valid_params_if(LOCK_CORE, lock_num < NUM_SPIN_LOCKS);
     core->spin_lock = spin_lock_instance(lock_num);
 }