efi: Allow efi=runtime

[ Upstream commit 71bef7da4112ed2677d4f10a58202a5a4638fb90 ]

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

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>