boards: Quark SE based boards have a different SPI interrupt flag

SPI needs to get its interrupt configured as triggering on level high to
work properly. This is specific to Quark SE (thus x86 core).

Change-Id: If3921240709e0fbf5b26e2325f67eb977a9fac10
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>