pinctrl: dra: dt-bindings: Fix pull enable/disable

The DRA74/72 control module pins have a weak pull up and pull down.
This is configured by bit offset 17. if BIT(17) is 1, a pull up is
selected, else a pull down is selected.

However, this pull resisstor is applied based on BIT(16) -
PULLUDENABLE - if BIT(18) is *0*, then pull as defined in BIT(17) is
applied, else no weak pulls are applied. We defined this in reverse.

Reference: Table 18-5 (Description of the pad configuration register
bits) in Technical Reference Manual Revision (DRA74x revision Q:
SPRUHI2Q Revised June 2014 and DRA72x revision F: SPRUHP2F - Revised
June 2014)

Fixes: 6e58b8f1 ("ARM: dts: DRA7: Add the dts files for dra7 SoC and dra7-evm board")
Signed-off-by: Nishanth Menon <nm@ti.com>
Tested-by: Felipe Balbi <balbi@ti.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>