sparc: add export.h to arch/sparc files as required

These files are only exporting symbols, so they don't need
the full module.h header file.  Previously they were getting
access to EXPORT_SYMBOL implicitly via overuse of module.h
from within other .h files, but that is being cleaned up.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>