r8152: split rtl8152_suspend function

[ Upstream commit 8fb28061 ]

Split rtl8152_suspend() into rtl8152_system_suspend() and
rtl8152_rumtime_suspend().

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>