Follow-up to #494. Storm control (#455) was merged after it and brings
three objects in code space without const: the extern declaration of
machine in rtl837x_storm.c and the name tables storm_types and
storm_names. SDCC 4.6.0 reports them as warnings 356 and 357, which
fail the build with CI=1 (--Werror). SDCC 4.5, which the CI uses, does
not report them.
The declarations now take the form used in the rest of the tree, as in
mime_strings in httpd.c. The images for KP_9000_6XHML_X2 and
KP_9000_9XHML_X_V3_1 are byte-identical before and after.
