efi: Runtime-wrapper: Get rid of the rtc_lock spinlock

efi: Runtime-wrapper: Get rid of the rtc_lock spinlock

The rtc_lock spinlock aims to serialize access to the CMOS RTC
between the UEFI firmware and the kernel drivers that use it
directly. However, x86 is the only arch that performs such
direct accesses, and that never uses the time related UEFI
runtime services. Since no other UEFI enlightened architectures
have a legcay CMOS RTC anyway, we can remove the rtc_lock
spinlock entirely.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1454364428-494-7-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>