ARM: dts: dra7: Fix suspend warning for vpe powerdomain

We currently are getting the following warning after a system suspend:

Powerdomain (vpe_pwrdm) didn't enter target state 0

Looks like this is because the STANDBYMODE bit for SMART_IDLE should
not be used. The TRM "Table 12-348. VPE_SYSCONFIG" says that the value
for SMART_IDLE is "0x2: Same behavior as bit-field value of 0x1". But
if the SMART_IDLE value is used, PM_VPE_PWRSTST LASTPOWERSTATEENTERED
bits always show value of 3.

Let's fix the issue by dropping SMART_IDLE for vpe. And let's also add
the missing the powerdomain for vpe.

Fixes: 1a2095160594 ("ARM: dts: dra7: Add ti-sysc node for VPE")
Cc: Benoit Parrot <[e-mail]>
Reported-by: Kevin Hilman <[e-mail]>
Reviewed-by: Kevin Hilman <[e-mail]>
Tested-by: Kevin Hilman <[e-mail]>
Signed-off-by: Tony Lindgren <[e-mail]>

arch/arm/boot/dts/dra7-l4.dtsi

···
 			reg = <0x1d0010 0x4>;
 			reg-names = "sysc";
 			ti,sysc-midle = <SYSC_IDLE_FORCE>,
-					<SYSC_IDLE_NO>,
-					<SYSC_IDLE_SMART>;
+					<SYSC_IDLE_NO>;
 			ti,sysc-sidle = <SYSC_IDLE_FORCE>,
 					<SYSC_IDLE_NO>,
 					<SYSC_IDLE_SMART>;
+			power-domains = <&prm_vpe>;
 			clocks = <&vpe_clkctrl DRA7_VPE_VPE_CLKCTRL 0>;
 			clock-names = "fck";
 			#address-cells = <1>;