treewide: Replace TRUE/FALSE with true/false

C language standard uses true/false for the boolean type.
Let's switch to that for better language compatibility.

Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Tested-by: Samuel Holland <samuel@sholland.org>

lib/sbi/sbi_console.c

@@ -20,9 +20,9 @@ bool sbi_isprintable(char c)
 {
 	if (((31 < c) && (c < 127)) || (c == '\f') || (c == '\r') ||
 	    (c == '\n') || (c == '\t')) {
-		return TRUE;
+		return true;
 	}
-	return FALSE;
+	return false;
 }
 
 int sbi_getc(void)