config: Remove hold_current from sample configs and sample macros

Now that the documentation recommends that hold_current not be set,
update the example config files to not specify a hold_current.

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

config/generic-th3d-ezboard-lite-v1.2.cfg

@@ -33,7 +33,6 @@ position_max: 350
 uart_pin: P0.5
 tx_pin: P0.4
 run_current: 0.600
-hold_current: 0.500
 stealthchop_threshold: 999999
 
 [stepper_y]
@@ -50,7 +49,6 @@ position_max: 350
 uart_pin: P0.11
 tx_pin: P0.10
 run_current: 0.600
-hold_current: 0.500
 stealthchop_threshold: 999999
 
 [stepper_z]
@@ -67,7 +65,6 @@ position_max: 400
 uart_pin: P0.20
 tx_pin: P0.19
 run_current: 0.700
-hold_current: 0.600
 stealthchop_threshold: 999999
 
 [extruder]
@@ -92,7 +89,6 @@ max_temp: 210
 uart_pin: P0.21
 tx_pin: P0.22
 run_current: 0.800
-hold_current: 0.700
 stealthchop_threshold: 999999
 
 [heater_bed]