i965: batchbuffer: write correct canonical offset with softpin

i965: batchbuffer: write correct canonical offset with softpin

Addresses in the command streams should be in canonical form (i.e
bit[63:48] == bit[47]). If the [bo->gtt_offset, bo->gtt_offset +
target_offset] range contains the address 0x800000000000, the current
code will fail that criteria.

v2: Fix missing include (Lionel)

Fixes: 1c9053d0765dc6 ("i965: Prepare batchbuffer module for softpin support.")
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>