ipq806x: increase drive-strength for pinmux

ipq806x: increase drive-strength for pinmux

Increase drive-strength from
https://lore.kernel.org/patchwork/patch/626885/

2mA drive strength is not enough when we connect multiple i2c devices
on the bus with different pull up resistors.

This issue was detected when multiple i2c devices
connected on the other side of level shifters on Linaro sensor board.
Maxing up to 16mA made i2c much stable.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>