brcm: Fix filename for BCM43430 NVRAM for the Raspberry Pi 3 Model B

BCM43430 NVRAM config file for the RPi3 Model B was set to the value
found by brcmf_dmi_probe(), but should use the DT compatible.
Rename the file to actually make it work with the kernel driver.

Signed-off-by: Matthias Brugger <mbrugger@suse.com>