AP_HAL_Linux: removed assert calls

these waste flash space and do not do us any good

libraries/AP_HAL_Linux/GPIO_RPI.cpp

@@ -198,7 +198,6 @@ void GPIO_RPI::pinMode(uint8_t pin, uint8_t output)
 
 void GPIO_RPI::pinMode(uint8_t pin, uint8_t output, uint8_t alt)
 {
-    assert(alt < 6);
     if (output == HAL_GPIO_INPUT) {
         set_gpio_mode_in(pin);
     } else if (output == HAL_GPIO_ALT) {

libraries/AP_HAL_Linux/HAL_Linux_Class.cpp

@@ -296,8 +296,6 @@ void HAL_Linux::run(int argc, char* const argv[], Callbacks* callbacks) const
     const char *module_path = AP_MODULE_DEFAULT_DIRECTORY;
 #endif
     
-    assert(callbacks);
-
     int opt;
     const struct GetOptLong::option options[] = {
         {"uartA",         true,  0, 'A'},

libraries/AP_HAL_Linux/I2CDevice.cpp

@@ -162,8 +162,6 @@ bool I2CDevice::transfer(const uint8_t *send, uint32_t send_len,
     struct i2c_msg msgs[2] = { };
     unsigned nmsgs = 0;
 
-    assert(_bus.fd >= 0);
-
     if (send && send_len != 0) {
         msgs[nmsgs].addr = _address;
         msgs[nmsgs].flags = 0;
@@ -389,8 +387,6 @@ I2CDeviceManager::_create_device(I2CBus &b, uint8_t address) const
 
 void I2CDeviceManager::_unregister(I2CBus &b)
 {
-    assert(b.ref > 0);
-
     if (--b.ref > 0) {
         return;
     }

libraries/AP_HAL_Linux/SPIDevice.cpp

@@ -274,8 +274,6 @@ bool SPIDevice::transfer(const uint8_t *send, uint32_t send_len,
     unsigned nmsgs = 0;
     int fd = _bus.fd[_desc.subdev];
 
-    assert(fd >= 0);
-
     if (send && send_len != 0) {
         msgs[nmsgs].tx_buf = (uint64_t) send;
         msgs[nmsgs].rx_buf = 0;
@@ -355,8 +353,6 @@ bool SPIDevice::transfer_fullduplex(const uint8_t *send, uint8_t *recv,
     struct spi_ioc_transfer msgs[1] = { };
     int fd = _bus.fd[_desc.subdev];
 
-    assert(fd >= 0);
-
     if (!send || !recv || len == 0) {
         return false;
     }