clk: rockchip: add PVTM clocks on rk3288

Process-Voltage-Temperatiure Monitor block on RK3288 has two clocks:
PVTM_CORE and PVTM_GPU.

Signed-off-by: Huang Lin <hl@rock-chips.com>
Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>