Remove the need to specify NUM_OF_ENCODERS for the Encoder feature (#6328)

* Remove the need to set NUM_OF_ENCODERS

Instead, calculate the size of the array, and use that instead

* Add hack for split common support

* Remove NUM_OF_ENCODERS from keyboard config

Can be reverted, if needed

keyboards/rgbkb/zygomorph/rev1/config.h

@@ -40,7 +40,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #define SOFT_SERIAL_PIN D3
 
-#define NUMBER_OF_ENCODERS 1
 #define ENCODERS_PAD_A  { D2 }
 #define ENCODERS_PAD_B  { D7 }