wifi: rt2x00: use explicitly signed or unsigned types
On some platforms, `char` is unsigned, but this driver, for the most part, assumed it was signed. In other places, it uses `char` to mean an unsigned number, but only in cases when the values are small. And in still other places, `char` is used as a boolean. Put an end to this confusion by declaring explicit types, depending on the context. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Stanislaw Gruszka <stf_xl@wp.pl> Cc: Helmut Schaa <helmut.schaa@googlemail.com> Cc: Kalle Valo <kvalo@kernel.org> Signed-off-by:Jason A. Donenfeld <Jason@zx2c4.com> Acked-by: