i965: Use the new drm_intel_bo offset64 field.

i965: Use the new drm_intel_bo offset64 field.

libdrm 2.4.52 introduces a new 'uint64_t offset64' field, intended to
replace the old 'unsigned long offset' field.  To preserve ABI, libdrm
continues to store the presumed offset in both locations.

On Broadwell, a 64-bit kernel may place BOs at "high" (> 4G) addresses.
However, with a 32-bit userspace, the 'unsigned long offset' field will
only be 32-bit, which is not large enough to hold this value.  We need
to use a proper uint64_t (like the kernel does).

Technically, a lot of this code doesn't affect Broadwell, so we could
leave it using the old field.  But it makes sense to just switch to the
new, properly typed field.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>