efi: Make efi_rts_work accessible to efi page fault handler

efi: Make efi_rts_work accessible to efi page fault handler

After the kernel has booted, if any accesses by firmware causes a page
fault, the efi page fault handler would freeze efi_rts_wq and schedules
a new process. To do this, the efi page fault handler needs
efi_rts_work. Hence, make it accessible.

There will be no race conditions in accessing this structure, because
all the calls to efi runtime services are already serialized.

Tested-by: Bhupesh Sharma <[email protected]>
Suggested-by: Matt Fleming <[email protected]>
Based-on-code-from: Ricardo Neri <[email protected]>
Signed-off-by: Sai Praneeth Prakhya <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>