drm/i915/gvt: Fix uninitialized variable in handle_mmio()

This code prints the wrong variable in the warning message.  It should
print "i" instead of "info->offset".  On the first iteration "info" is
uninitialized leading to a crash and on subsequent iterations it prints
the previous offset instead of the current one.

Fixes: e0f74ed4

 ("i915/gvt: Separate the MMIO tracking table from GVT-g")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/11957c20-b178-4027-9b0a-e32e9591dd7c@moroto.mountain
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>