uru4000: Fix integer overflow in imaging_run_state()
Motivation:
- When ‘buf[0]’ cannot handle more than maximum value of ‘char’ (i.e., > 127), the variable may lead to an overflow.
- ‘img->key_number’ which has a type of ‘uint8_t’ has only been assigned to ‘buf[0]’.
- It is probably a good idea to replace type of ‘buf[]’; from ‘char’ to ‘unsigned char’.
Modification:
- Correct the above issue
- Correctly declare type of the variable against overflow