pwm: fsl-ftm: Added the support of per-compatible data

On the i.MX8x SoC family, an additional PWM enable bit is added for each
PWM channel in the register FTM_SC[23:16]. It supports 8 channels. Bit
16 is for channel 0, and bit 23 is for channel 7. As the IP version
information can not be obtained via any of the FTM registers, a property
of "has_enable_bits" is added via per-compatible data structure.

Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>