Handle case where debugfs not already mounted

[jadonk]

From @jadonk on December 16, 2013 15:27

getPinMode() will fail to fetch the mux mode if /sys/kernel/debug/pinctrl/44e10800.pinmux/pins isn't already mounted.

Mount command is:
mount -t debugfs none /sys/kernel/debug/

Need to find a good place to put this.

Copied from original issue: jadonk#61

[jadonk]

Issue still exists in 0.2.4.