efi_loader: remove comparisons to string literals from runtime

efi_loader: remove comparisons to string literals from runtime

For EFI runtime services, we manage to preserve string literals
by placing the .efi_runtime section just before .data and preserving
it when marking the runtime memory by marking surrounding boottime
code as runtime. This is ok for now but will break if we update any
linker scripts and decouple .text and .runtime sections.

So let's define the strings we used to compare in the appropriate
section for runtime services

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Mark Kettenis <kettenis@openbsd.org>