brcm: remove old brcm firmwares that have newer cypress variants

brcm: remove old brcm firmwares that have newer cypress variants

Cypress pushed newer versions of the following firmwares:

     - 43012
     - 43340
     - 43362
     - 4339
     - 43430
     - 43455
     - 4354
     - 4356
     - 43570
     - 4373
     - 54591

Remove these old ones as they're likely vulnerable to at least the
KrØØk vulnerability (CVE-2019-15126).

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Chi-Hsien Lin <chi-hsien.lin@cypress.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>