readq/writeq: Add explicit lo_hi_[read|write]_q and hi_lo_[read|write]_q

readq/writeq: Add explicit lo_hi_[read|write]_q and hi_lo_[read|write]_q

Even on x86-64, I've found the need to break up a readq() into 2 readl()
calls. According to the Intel datasheet for the E3-1200 processor:

"
Software must not access B0/D0/F0 32-bit memory-mapped registers with
requests that cross a DW boundary.
"

(http://www.intel.com/content/www/us/en/processors/xeon/xeon-e3-1200-family-vol-2-datasheet.html p. 16)

I can confirm this is true via several hard machine lockups.

Thus, add explicit hi_lo_[readq|write]_q and lo_hi_[read|write]_q so that these
uses are spelled out.

Signed-off-by: Jason Baron <jbaron@akamai.com>
Link: http://lkml.kernel.org/r/281f09da7ad01e5cea99737ec34d2399bdbbbf63.1403818526.git.jbaron@akamai.com
Signed-off-by: Borislav Petkov <bp@suse.de>