cxl: Add explicit precision specifiers

C99 says that a precision given as simply '.' with no following digits
or * should be interpreted as 0. The kernel's printf implementation,
however, treats this case as if the precision was omitted. C99 also
says that if both the precision and value are 0, no digits should be
printed. Even if the kernel followed C99 to the letter, I don't think
that would be particularly useful in these cases. For consistency with
most other format strings in the file, use an explicit precision of 16
and add a 0x prefix.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>