output_pin: Deprecate static_value parameter

Remove support for configuring "static" pins in output_pin module.  A
"static" pin only saves a few bytes of memory in the micro-controller.
The savings does not justify the increased code complexity.

Deprecate the static_value parameter to warn users.  In the interim, a
static_value parameter will set both value and shutdown_value
parameters.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

config/printer-adimlab-2018.cfg

@@ -89,7 +89,7 @@ pwm: True
 scale: 2.0
 cycle_time: .000030
 hardware_pwm: True
-static_value: 1.3
+value: 1.3
 
 [output_pin stepper_z_current]
 pin: PL4
@@ -97,7 +97,7 @@ pwm: True
 scale: 2.0
 cycle_time: .000030
 hardware_pwm: True
-static_value: 1.3
+value: 1.3
 
 [output_pin stepper_e_current]
 pin: PL3
@@ -105,7 +105,7 @@ pwm: True
 scale: 2.0
 cycle_time: .000030
 hardware_pwm: True
-static_value: 1.25
+value: 1.25
 
 [display]
 lcd_type: st7920