archv7-m: removing the wrong args_in_out_different

- This commit removes the restriction in the `make()` function of `ldr`,
  `ldr_with_imm`, `ldrb_with_imm` and  `ldrh_with_imm`, namely the line:

  `obj.args_in_out_different = [(0, 0)] # Can't have Rd==Ra`.

- This restriction makes it harder for Slothy to find a solution
  in scenarios where the number of available registers was limited.

Signed-off-by: willieyz <willie.zhao@chelpis.com>

Author: willieyz

slothy/targets/arm_v7m/arch_v7m.py

@@ -1911,7 +1911,6 @@ def make(cls, src):
         obj.increment = None
         obj.pre_index = 0
         obj.addr = obj.args_in[0]
-        obj.args_in_out_different = [(0, 0)]  # Can't have Rd==Ra
         return obj
 
     def write(self):
@@ -1932,7 +1931,6 @@ def make(cls, src):
         obj.increment = None
         obj.pre_index = obj.immediate
         obj.addr = obj.args_in[0]
-        obj.args_in_out_different = [(0, 0)]  # Can't have Rd==Ra
         return obj
 
     def write(self):
@@ -1957,7 +1955,6 @@ def make(cls, src):
         obj = Armv7mInstruction.build(cls, src)
         obj.increment = None
         obj.pre_index = obj.immediate
-        obj.args_in_out_different = [(0, 0)]  # Can't have Rd==Ra
         obj.addr = obj.args_in[0]
         return obj
 
@@ -1976,7 +1973,6 @@ def make(cls, src):
         obj = Armv7mInstruction.build(cls, src)
         obj.increment = None
         obj.pre_index = obj.immediate
-        obj.args_in_out_different = [(0, 0)]  # Can't have Rd==Ra
         obj.addr = obj.args_in[0]
         return obj