gem5: Add readq and writeq support to arch/arm/include/asm/io.h Update asm/io.h to provide known working implementations for writeq and readq to work with NVMe and IGB device drivers which perform 64-bit IO reads and writes. Signed-off-by: Geoffrey Blake <Geoffrey.Blake@arm.com> Change-Id: I1ec9bad6fc9d0ef4eda2f71200bc3e08460dcacf Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>