bcm53xx: move bcm47xx_sprom driver to 4.4 specific directory

In kernel 4.9 it's already present so we don't want to overwite it (with
older & API incompatible version).

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

diff --git a/target/linux/bcm53xx/files/drivers/firmware/broadcom/bcm47xx_sprom.c b/target/linux/bcm53xx/files-4.4/drivers/firmware/broadcom/bcm47xx_sprom.c
similarity index 100%
rename from target/linux/bcm53xx/files/drivers/firmware/broadcom/bcm47xx_sprom.c
rename to target/linux/bcm53xx/files-4.4/drivers/firmware/broadcom/bcm47xx_sprom.c