soc/intel/skylake: Make use of Intel SPI common block

TEST=Build and boot soraka/eve

Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Change-Id: I10de3ff75a3b063c4c46471e380bbbe2630c35f3
Reviewed-on: https://review.coreboot.org/22361
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
3 files changed