drm/i915: pin: delete duplicate check in intel_pin_and_fence_fb_obj()

The "ret" variable is checked on the previous line so we know it's
zero.  No need to check again.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211109114850.GB16587@kili