drm/i915/vma: fix struct i915_vma_bindinfo kernel-doc

You can't document both a sub-struct type and a struct member at the
same time. Separate them.

drivers/gpu/drm/i915/i915_vma_resource.h:91: warning: Incorrect use of kernel-doc format:          * struct i915_vma_bindinfo - Information needed for async bind
drivers/gpu/drm/i915/i915_vma_resource.h:129: warning: Function parameter or member 'bi' not described in 'i915_vma_resource'

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/89ab5cf179566c429383cc57db746038f75cba0d.1683041799.git.jani.nikula@intel.com