ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL*

With the previous refactoring, you can always use EXPORT_SYMBOL*.

Replace two instances in ia64, then remove EXPORT_DATA_SYMBOL*.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>