clk: ti: dra7: Drop idlest polling from IVA clkctrl clocks

Similar to what we've done for IPU and DSP let's ignore the status bit
for the IVA clkctrl register.

The clkctrl status won't change unless the related rstctrl is deasserted,
and the rstctrl status won't change unless the clkctrl is enabled.

Cc: linux-clk@vger.kernel.org
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Suman Anna <s-anna@ti.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>