pncconf -change some text so users don't select BLDC option

Users were seeing 'bruchless motor control' and selecting that option
even when they didn't need it for their BL motors.
Changed the help text to point out it is uusual to use BLDC options.
pncconf -add pwm invert output to tests and HAL file

so one can invert the pulse and or direction of the PWM
also added step / direction inversion to tune test