These are never modified, so make them const to allow the compiler to put
them in read-only memory. It also allows the compiler to shrink the
resulting module with ~900 bytes, test-built with gcc 10.2 on x86_64.
text data bss dec hex filename
204377 42832 576 247785 3c7e9 drivers/hid/wacom_old.ko
204240 42064 576 246880 3c460 drivers/hid/wacom_new.ko