drivers/i2c/i2c_dw.c is not 64-bit clean

[ghost]

Build hello_world for the up_squared target with CONFIG_X86_LONGMODE and a bunch of warnings occur. This is harmless, but our code should build without warnings, of course.

/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c:46:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   (struct i2c_dw_registers *)dw->base_address;
   ^
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c: In function 'i2c_dw_data_read':
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c:100:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   (struct i2c_dw_registers *)dw->base_address;
   ^
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c: In function 'i2c_dw_data_send':
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c:128:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   (struct i2c_dw_registers *)dw->base_address;
   ^
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c: In function 'i2c_dw_transfer_complete':
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c:173:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   (struct i2c_dw_registers *)dw->base_address;
   ^
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c: In function 'i2c_dw_isr':
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c:190:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   (struct i2c_dw_registers *)dw->base_address;
   ^
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c: In function 'i2c_dw_setup':
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c:269:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   (struct i2c_dw_registers *)dw->base_address;
   ^
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c: In function 'i2c_dw_transfer':
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c:397:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   (struct i2c_dw_registers *)dw->base_address;
   ^
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c: In function 'i2c_dw_runtime_configure':
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c:506:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   (struct i2c_dw_registers *)dw->base_address;
   ^
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c: In function 'i2c_dw_initialize':
/home/charles/zephyr/zephyr/drivers/i2c/i2c_dw.c:628:9: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  regs = (struct i2c_dw_registers *) dw->base_address;```