efi: Allow efi=runtime

In case the command line option "efi=noruntime" is default at built-time, the user
could overwrite its state by `efi=runtime' and allow it again.

This is useful on PREEMPT_RT where "efi=noruntime" is default and the
user might need to alter the boot order for instance.

Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/efi.c

@@ -97,6 +97,9 @@ static int __init parse_efi_cmdline(char *str)
 	if (parse_option_str(str, "noruntime"))
 		disable_runtime = true;
 
+	if (parse_option_str(str, "runtime"))
+		disable_runtime = false;
+
 	if (parse_option_str(str, "nosoftreserve"))
 		set_bit(EFI_MEM_NO_SOFT_RESERVE, &efi.flags);