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-fysetc-cheetah-v1.2.cfg

@@ -24,7 +24,6 @@ homing_speed: 50
 uart_pin: PA12
 tx_pin: PA11
 run_current: 0.800
-hold_current: 0.500
 stealthchop_threshold: 999999
 
 [stepper_y]
@@ -42,7 +41,6 @@ homing_speed: 50
 uart_pin: PB7
 tx_pin: PB6
 run_current: 0.800
-hold_current: 0.500
 stealthchop_threshold: 999999
 
 [stepper_z]
@@ -59,7 +57,6 @@ position_max: 200
 uart_pin: PB11
 tx_pin: PB10
 run_current: 0.800
-hold_current: 0.500
 stealthchop_threshold: 999999
 
 [extruder]
@@ -84,7 +81,6 @@ max_temp: 250
 uart_pin: PA3
 tx_pin: PA2
 run_current: 1.0
-hold_current: 0.500
 stealthchop_threshold: 999999
 
 [heater_bed]