via: fix warnings with -Wdiscarded-qualifiers
via/mm-plugin-via.c: In function ‘mm_plugin_create’:
via/mm-plugin-via.c:59:54: error: initialization discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
59 | static const mm_str_pair product_strings[] = { { "via", "cbp7" },
| ^~~~~
via/mm-plugin-via.c:59:64: error: initialization discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
59 | static const mm_str_pair product_strings[] = { { "via", "cbp7" },
| ^~~~~~
via/mm-plugin-via.c:60:54: error: initialization discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
60 | { "fusion", "2770p" },
| ^~~~~~~~
via/mm-plugin-via.c:60:64: error: initialization discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
60 | { "fusion", "2770p" },
| ^~~~~~~