soc/intel/skylake/irq.c: Fix undefined `memcpy()`

soc/intel/skylake/irq.c: Fix undefined `memcpy()`

The original value of the `DevIntConfigPtr` is unknown, and there's no
way to be absolutely certain that it actually points to usable memory.
Instead of copying the data, update the pointer's address to reference
the global variable directly. It is assumed that FSP does not write to
the memory pointed by `DevIntConfigPtr`. Confirming this assumption is
pointless; one might as well reimplement FSP instead.

Change-Id: I90594cc09e3fa2aef98658441c323a44a869635b
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65217
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>