Reducing the size of struct printf_spec is a good thing because multiple
instances are commonly passed on stack.

It's possible for type to be u8 and field_width to be s8, but this is
likely small enough for now.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>