linux_spi: reorder includes for linux <4.14

This works around a missing header in spidev.h present in older
versions of Linux. Patch is ported from:
https://git.buildroot.net/buildroot/tree/package/flashrom/0001-spi.patch



Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: David Hendricks <david.hendricks@gmail.com>
Change-Id: Ieab60f59bc63aca0dc4867f31699dab4167da05b
Reviewed-on: https://review.coreboot.org/c/flashrom/+/35830


Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>