use new sysfs.c C extension in pwm.py
use new sysfs.c C extension in pwm.py

graycatlabs/PyBBIO,leftbrainstrain/PyBBIO,leftbrainstrain/PyBBIO,graycatlabs/PyBBIO,graycatlabs/PyBBIO,ims-tyler/PyBBIO,ims-tyler/PyBBIO,leftbrainstrain/PyBBIO,ims-tyler/PyBBIO,leftbrainstrain/PyBBIO,graycatlabs/PyBBIO,ims-tyler/PyBBIO,graycatlabs/PyBBIO,ims-tyler/PyBBIO,leftbrainstrain/PyBBIO