Adding GPIO pins for the BeagleBone Black

Adding GPIO pins for the BeagleBone Black

Add all the possible GPIO pins on the P8 and P9 headers
of the BeagleBone Black.

Source of GPIO pins numbers is:
https://github.com/adafruit/adafruit-beaglebone-io-python/blob/master/source/common.c

GPIO pins on BeagleBone Black:
P8_3
P8_4
P8_5
P8_6
P8_7
P8_8
P8_9
P8_10
P8_11
P8_12
P8_13
P8_14
P8_15
P8_16
P8_17
P8_18
P8_19
P8_20
P8_21
P8_22
P8_23
P8_24
P8_25
P8_26
P8_27
P8_28
P8_29
P8_30
P8_31
P8_32
P8_33
P8_34
P8_35
P8_36
P8_37
P8_38
P8_39
P8_40
P8_41
P8_42
P8_43
P8_44
P8_45
P8_46
P9_11
P9_12
P9_13
P9_14
P9_15
P9_16
P9_17
P9_18
P9_19
P9_20
P9_21
P9_22
P9_23
P9_24
P9_25
P9_26
P9_27
P9_28
P9_29
P9_30
P9_31
P9_41
P9_42