hpet: Remove unnecessary NULL check before unregister_sysctl_table()

unregister_sysctl_table() checks for NULL pointers internally.
Remove unneeded NULL check here.

Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Link: https://lore.kernel.org/r/20250514032637.2317639-1-nichen@iscas.ac.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Chen Ni

drivers/char/hpet.c

@@ -1023,8 +1023,7 @@ static int __init hpet_init(void)
 
 	result = acpi_bus_register_driver(&hpet_acpi_driver);
 	if (result < 0) {
-		if (sysctl_header)
-			unregister_sysctl_table(sysctl_header);
+		unregister_sysctl_table(sysctl_header);
 		misc_deregister(&hpet_misc);
 		return result;
 	}