tmem: Use 'struct xen_tmem_oid' for every user.

tmem: Use 'struct xen_tmem_oid' for every user.

Patch "tmem: Make the uint64_t oid[3] a proper structure:
xen_tmem_oid" converted the sysctl API to use an
proper structure. But it did not do it for the tmem hypercall.

This expands that and converts the tmem hypercall. For this
to work we define the struct in tmem.h and include it in
sysctl.h.

This change also included work to make the compat layer
happy. That was to declare the struct xen_tmem_oid to be
checked in xlat.lst - which will construct an typedef
in the compat file with the same type, hence allowing
copying of 'oid' member without type issues. The kicker
is that the compat layer adds the prefix 'xen' and since
our structure already has it - we must not include it.

The layout (and size) of this structure in memory for the
'struct tmem_op' (so guest facing) is the same! Verified
via pahole and with 32/64 bit guests.

--- /tmp/old    2015-08-27 16:34:00.535638730 -0400
+++ /tmp/new    2015-08-27 16:34:10.447705328 -0400
@@ -8,7 +8,7 @@
                        uint32_t   arg1;                 /*    28     4 */
                } creat;                                 /*          24 */
                struct {
-                       uint64_t   oid[3];               /*     8    24 */
+                       xen_tmem_oid_t oid;              /*     8    24 */
                        uint32_t   index;                /*    32     4 */
                        uint32_t   tmem_offset;          /*    36     4 */
                        uint32_t   pfn_offset;           /*    40     4 */

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Jen Beulich <jbeulich@suse.com>