of: Fix missing includes - ll_temac

It is the next patch which is fixing missing header
which were removed from prom.h.

Related patches:
"of/address: Clean up function declarations" (sha1 id 22ae782f)
"of: Fix missing includes" (sha1 id f1ca09b2

)

Signed-off-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>