motor.c: Wrong values for ui8_phase_x_voltage and MIDDLE_PWM_DUTY_CYCLE_MAX

[mspider65]

Since PWM frequency was increased and PWM counter goes up to 420 (before 511), the computed values of ui8_phase_x_voltage should be less than 210 (before 254).
Both MIDDLE_PWM_DUTY_CYCLE_MAX and ui8_svm_table values should be updated.