AP_HAL_Linux: Led_Sysfs: small fixes

- avoid trying to close fd when it's -1

  - Keep includes sorted

  - AP_HAL::panic() doesn't need \n terminator

  - %u requires unsigned type

  - #pragma once is the first thing on a header

libraries/AP_HAL_Linux/Led_Sysfs.cpp

@@ -19,9 +19,9 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <inttypes.h>
 #include <unistd.h>
 
 #include <AP_HAL/AP_HAL.h>
@@ -37,7 +37,7 @@ Led_Sysfs::Led_Sysfs(const char *led_name)
 
 Led_Sysfs::~Led_Sysfs()
 {
-    if (_brightness_fd) {
+    if (_brightness_fd >= 0) {
         close(_brightness_fd);
     }
 }
@@ -48,7 +48,7 @@ bool Led_Sysfs::init()
     char *max_br_path;
 
     if (asprintf(&br_path, "/sys/class/leds/%s/brightness", _led_name) == -1) {
-        AP_HAL::panic("LinuxLed_Sysfs : Couldn't allocate brightness path\n");
+        AP_HAL::panic("LinuxLed_Sysfs : Couldn't allocate brightness path");
     }
 
     _brightness_fd = open(br_path, O_WRONLY | O_CLOEXEC);
@@ -59,11 +59,11 @@ bool Led_Sysfs::init()
     }
 
     if (asprintf(&max_br_path, "/sys/class/leds/%s/max_brightness", _led_name) == -1) {
-        AP_HAL::panic("LinuxLed_Sysfs : Couldn't allocate max_brightness path\n");
+        AP_HAL::panic("LinuxLed_Sysfs : Couldn't allocate max_brightness path");
     }
 
     if (Util::from(hal.util)->read_file(max_br_path, "%u", &_max_brightness) < 0) {
-        AP_HAL::panic("LinuxLed_Sysfs : Unable to read max_brightness in %s\n",
+        AP_HAL::panic("LinuxLed_Sysfs : Unable to read max_brightness in %s",
                       max_br_path);
     }
 
@@ -79,7 +79,7 @@ bool Led_Sysfs::set_brightness(uint8_t brightness)
         return false;
     }
 
-    int br = brightness * _max_brightness / UINT8_MAX;
+    unsigned int br = brightness * _max_brightness / UINT8_MAX;
 
     /* Don't log fails since this could spam the console */
     if (dprintf(_brightness_fd, "%u", br) < 0) {

libraries/AP_HAL_Linux/Led_Sysfs.h

@@ -14,14 +14,13 @@
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
+#pragma once
 
 #include <AP_HAL/AP_HAL.h>
 
 #include "AP_HAL_Linux.h"
 #include "Util.h"
 
-#pragma once
-
 namespace Linux {
 
 class Led_Sysfs {