drivers: led: Fix warnings in shell_print

Change format in various shell_error calls from int to long unsigned
int.

Warning:

    warning: format '%d' expects argument of type 'int', but argument
    6 has type 'long unsigned int'

Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
diff --git a/drivers/led/led_shell.c b/drivers/led/led_shell.c
index df9fa26..f12b11e 100644
--- a/drivers/led/led_shell.c
+++ b/drivers/led/led_shell.c
@@ -142,12 +142,12 @@
 		return -EINVAL;
 	}
 	if (value > 100) {
-		shell_error(shell, "Invalid LED brightness value %d (max 100)",
+		shell_error(shell, "Invalid LED brightness value %lu (max 100)",
 			    value);
 		return -EINVAL;
 	}
 
-	shell_print(shell, "%s: setting LED %d brightness to %d",
+	shell_print(shell, "%s: setting LED %d brightness to %lu",
 		    dev->name, led, value);
 
 	err = led_set_brightness(dev, led, (uint8_t) value);
@@ -192,7 +192,7 @@
 		}
 		if (col > 255) {
 			shell_error(shell,
-				    "Invalid LED color value %d (max 255)",
+				    "Invalid LED color value %lu (max 255)",
 				    col);
 			return -EINVAL;
 		}
@@ -234,12 +234,12 @@
 		return -EINVAL;
 	}
 	if (value > 255) {
-		shell_error(shell, "Invalid channel value %d (max 255)",
+		shell_error(shell, "Invalid channel value %lu (max 255)",
 			    value);
 		return -EINVAL;
 	}
 
-	shell_print(shell, "%s: setting channel %d to %d",
+	shell_print(shell, "%s: setting channel %d to %lu",
 		    dev->name, channel, value);
 
 	err = led_set_channel(dev, channel, (uint8_t) value);
@@ -286,7 +286,7 @@
 		}
 		if (val > 255) {
 			shell_error(shell,
-				    "Invalid channel value %d (max 255)", val);
+				    "Invalid channel value %lu (max 255)", val);
 			return -EINVAL;
 		}
 		value[i] = val;