ARM: OMAP3: hwmod data: set sw control flag on dss hwmods

ARM: OMAP3: hwmod data: set sw control flag on dss hwmods

Without this hwmod's _setup() enables interface clock and leaves it on
forever supposedly for hw autoidle to manage. However this causes
clockdomain's reference counter to never return to zero and
omap3xxx_clkdm_clk_disable() never gets called to remove autoteps to
MPU, which means DSS ends up needlessly transitioning alog with the CPU.

This hack avoids such switching. It also makes context loss counter work
without need to call pwrdm_{pre,post}_transition on all power domains in
omap_sram_idle() as it's taken care by clkdm enable/disable.

Could not measure any power usage differences though.