drm/i915/gvt: Fix error code in intel_gvt_init_device()

drm/i915/gvt: Fix error code in intel_gvt_init_device()

The intel_gvt_init_vgpu_type_groups() function is only called from
intel_gvt_init_device().  If it fails then the intel_gvt_init_device()
prints the error code and propagates it back again.  That's a bug
because false is zero/success.  The fix is to modify it to return zero
or negative error codes and make everything consistent.

Fixes: c5d71cb31723 ("drm/i915/gvt: Move vGPU type related code into gvt file")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/YHaFQtk/DIVYK1u5@mwanda
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>