x86/boot: Change some static bootflag functions to bool

The return values of some functions are of boolean type. Change the
type of these function to bool and adjust their return values.

No functional change intended.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250129154920.6773-1-ubizjak@gmail.com

arch/x86/kernel/bootflag.c

@@ -20,7 +20,7 @@
 
 int sbf_port __initdata = -1;	/* set via acpi_boot_init() */
 
-static int __init parity(u8 v)
+static bool __init parity(u8 v)
 {
 	int x = 0;
 	int i;
@@ -30,7 +30,7 @@ static int __init parity(u8 v)
 		v >>= 1;
 	}
 
-	return x;
+	return !!x;
 }
 
 static void __init sbf_write(u8 v)
@@ -66,14 +66,14 @@ static u8 __init sbf_read(void)
 	return v;
 }
 
-static int __init sbf_value_valid(u8 v)
+static bool __init sbf_value_valid(u8 v)
 {
 	if (v & SBF_RESERVED)		/* Reserved bits */
-		return 0;
+		return false;
 	if (!parity(v))
-		return 0;
+		return false;
 
-	return 1;
+	return true;
 }
 
 static int __init sbf_init(void)