Fix more compile errors in bootloader_message_twrp

Change-Id: I3b1b540f404efcd153d0b75d29e5b6ee8b0caa85

bootloader_message_twrp/bootloader_message.cpp

@@ -310,11 +310,11 @@ get_args(int *argc, char ***argv) {
     }
     //stage = strndup(boot.stage, sizeof(boot.stage));
 
-    if (boot.command[0] != 0 && boot.command[0] != 255) {
+    if (boot.command[0] != 0 && boot.command[0] != (char)255) {
         printf("Boot command: %.*s\n", (int)sizeof(boot.command), boot.command);
     }
 
-    if (boot.status[0] != 0 && boot.status[0] != 255) {
+    if (boot.status[0] != 0 && boot.status[0] != (char)255) {
         printf("Boot status: %.*s\n", (int)sizeof(boot.status), boot.status);
     }