extensive orb_advert_t fixes

The calls to orb_advertise were being mishandled throughout the code.
There were ::close() calls on memory pointers, there were checks
against < 0 when it is a pointer to a object and values larger than
0x7ffffffff are valid. Some places orb_advert_t variables were
being initialized as 0 other places as -1.

The orb_advert_t type was changed to uintptr_t so the pointer value
would not be wrapped as a negative number. This was causing a failure
on ARM.

Tests for < 0 were changed to == 0 since a null pointer is the valid
representation for error, or uninitialized.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/drivers/batt_smbus/batt_smbus.cpp

@@ -203,7 +203,7 @@ BATT_SMBUS::BATT_SMBUS(int bus, uint16_t batt_smbus_addr) :
 	_enabled(false),
 	_work{},
 	_reports(nullptr),
-	_batt_topic(-1),
+	_batt_topic(0),
 	_batt_orb_id(nullptr),
 	_start_time(0),
 	_batt_capacity(0)
@@ -427,13 +427,13 @@ BATT_SMBUS::cycle()
 		}
 
 		// publish to orb
-		if (_batt_topic != -1) {
+		if (_batt_topic != 0) {
 			orb_publish(_batt_orb_id, _batt_topic, &new_report);
 
 		} else {
 			_batt_topic = orb_advertise(_batt_orb_id, &new_report);
 
-			if (_batt_topic < 0) {
+			if (_batt_topic == 0) {
 				errx(1, "ADVERT FAIL");
 			}
 		}