arm/efi: Replace open coded constants with symbolic ones

Replace the various open coded constants in the EFI PE/COFF header with
definitions from pe.h, or expressions based on local symbols.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170818194947.19347-11-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>