brcm: Fix Raspberry Pi 4B NVRAM file

NVRAM file set's boarflags3 to 0x48200100 which indicates the firmware
that an external LPO is present. But on the RPi4 no external LPO exists.

Fixes: 870b805d

 ("brcm: Update Raspberry Pi 3B+/4B NVRAM for downstream changes")
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>

brcm/brcmfmac43455-sdio.raspberrypi,4-model-b.txt

@@ -7,7 +7,7 @@ aa5g=1
 AvVmid_c0=1,165,2,100,2,100,2,100,2,100
 boardflags=0x00480201
 boardflags2=0x40800000
-boardflags3=0x48200100
+boardflags3=0x44200100
 boardrev=0x1304
 boardtype=0x6e4
 btc_mode=1