linux-firmware: Fix the linux-firmware-bcm4373 FILES variable

linux-firmware: Fix the linux-firmware-bcm4373 FILES variable

This commit includes the 'cyfmac4373-sdio.clm_blob' file in
the list of files for the linux-firmware-bcm4373 package.
Without this file, the linux-firmware package adds all
firmware packages to the image.

Signed-off-by: Rodrigo M. Duarte <rodrigo.duarte@ossystems.com.br>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit 7886d3b77200e4488393fa11c8198658fcf386cd)
Signed-off-by: Steve Sakoman <steve@sakoman.com>