i915: Replace "hweight8(dev_priv->info.subslice_7eu[i]) != 1" with...

i915: Replace "hweight8(dev_priv->info.subslice_7eu[i]) != 1" with "!is_power_of_2(dev_priv->info.subslice_7eu[i])"

Signed-off-by: Zeng Zhaoxiu <zhaoxiu.zeng@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449397590-14292-1-git-send-email-zhaoxiu.zeng@gmail.com