Davinci: support LPSC SwRstDisable state

The current clock control code always gates the clock (PSC state Disable = 2)
on clk_disable().  Some on-chip peripherals (e.g. LCD controller on TNETV107X)
need to be put into SwRstDisable = 0 on clock disable, to maintain
hardware sanity.

This patch extends the davinci_psc_config() arguments to pass in the desired
module state instead of a boolean enable/disable.  Further, clk_disable() now
checks for the PSC_SWRSTDISABLE clk flag before selecting the target state.

Signed-off-by: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>