net/tg3: use crc32() instead of hand-rolled equivalent

The calculation done by calc_crc() is equivalent to
~crc32(~0, buf, len), so just use that instead.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://patch.msgid.link/20250513041402.541527-1-ebiggers@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>