Add define to disable LEDs

[Tomblarom]

I added a define to disable the use of LEDs if the hardware misses them. In my case there where none, in order to use all GPIOs as external inputs. I took CAN_ENABLE as example. Obviously by default LED_ENABLE defined as 1 and only set to 0, if HW_HAS_NO_LED is set in the hwconf/hw_xx.h.

And I deleted a duplicate of #include "ledpwm.h" in the main.c file.

[Tomblarom]

According to @vedderb another solution would be to simply empty out the corresponding variables, like this:

#define LED_GREEN_ON()
#define LED_GREEN_OFF()
#define LED_RED_ON()
#define LED_RED_OFF()