ARM: davinci: da850: adopt to pinctrl-single change for configuring multiple pins

function-mask DT property is now a mask for a pin at each pin offset
inside a given pincontrol register. Fix DA850 DT data to reflect
this change.

Signed-off-by: Manjunathappa, Prakash <prakash.pm@ti.com>
[nsekhar@ti.com: reword commit message for clarity]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>