linux-firmware: Fix packaging

Upstream directory layout has changed after update in commit 3c2f8b750ab9c53773fb5a9a1a874e475740b4ee, resulting in some package to pull in linux-firmware base package.
This may cause an image size increase of approximately 700MB.

See log.do_packaging:
DEBUG: linux-firmware-bcm43340 contains dangling link /lib/firmware/cypress/cyfmac43340-sdio.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm43362 contains dangling link /lib/firmware/cypress/cyfmac43362-sdio.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm4339 contains dangling link /lib/firmware/cypress/cyfmac4339-sdio.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm43430 contains dangling link /lib/firmware/cypress/cyfmac43430-sdio.clm_blob
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm43430 contains dangling link /lib/firmware/cypress/cyfmac43430-sdio.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm43455 contains dangling link /lib/firmware/cypress/cyfmac43455-sdio.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm43455 contains dangling link /lib/firmware/cypress/cyfmac43455-sdio.clm_blob
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm4354 contains dangling link /lib/firmware/cypress/cyfmac4354-sdio.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm4356 contains dangling link /lib/firmware/cypress/cyfmac4356-sdio.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm4356-pcie contains dangling link /lib/firmware/cypress/cyfmac4356-pcie.clm_blob
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm4356-pcie contains dangling link /lib/firmware/cypress/cyfmac4356-pcie.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm43570 contains dangling link /lib/firmware/cypress/cyfmac43570-pcie.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-bcm4373 contains dangling link /lib/firmware/cypress/cyfmac4373-sdio.bin
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-netronome contains dangling link /lib/firmware/netronome/nic/nic_AMDA0099-0001_2x10.nffw
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-netronome contains dangling link /lib/firmware/netronome/nic/nic_AMDA0099-0001_2x25.nffw
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-netronome contains dangling link /lib/firmware/netronome/nic/nic_AMDA0081-0001_4x10.nffw
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-netronome contains dangling link /lib/firmware/netronome/nic/nic_AMDA0097-0001_8x10.nffw
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-netronome contains dangling link /lib/firmware/netronome/nic/nic_AMDA0099-0001_1x10_1x25.nffw
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-netronome contains dangling link /lib/firmware/netronome/nic/nic_AMDA0097-0001_2x40.nffw
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-netronome contains dangling link /lib/firmware/netronome/nic/nic_AMDA0096-0001_2x10.nffw
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-netronome contains dangling link /lib/firmware/netronome/nic/nic_AMDA0097-0001_4x10_1x40.nffw
DEBUG: target found in linux-firmware
DEBUG: linux-firmware-netronome contains dangling link /lib/firmware/netronome/nic/nic_AMDA0081-0001_1x40.nffw
DEBUG: target found in linux-firmware

Signed-off-by: Michael Trensch <mtrensch@hilscher.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit cd273c61)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>