linux-firmware-rpidistro: Fix WiFi on RaspberryPi 4

The official Raspbian with RPi4 support has an additional change for the
NVRAM WiFi configuration: boardflags3 value is changed from "0x48200100"
to "0x44200100". Without this change the interface never comes up. It is
confusing because the deb changelog doesn't say anything about it and
the repository upstream doesn't have this change. Asked for more info
here:
https://github.com/RPi-Distro/firmware-nonfree/issues/3

In the meanwhile we import this change. Also, we remove the .pc directory
which confuses the patch step.

Signed-off-by: Andrei Gherzan <andrei@gherzan.ro>

recipes-kernel/linux-firmware-rpidistro/linux-firmware-rpidistro/0001-brcmfmac43455-sdio.txt-Follow-raspbian-change-for-bo.patch

@@ -0,0 +1,39 @@
+From c9d4f263131cb8e62597e0a296968b5cdbfe0019 Mon Sep 17 00:00:00 2001
+From: Andrei Gherzan <andrei@gherzan.ro>
+Date: Thu, 27 Jun 2019 20:49:10 +0100
+Subject: [PATCH] brcmfmac43455-sdio.txt: Follow raspbian change for
+ boardflags3
+
+Without this change the WiFi interface on RPi4 never comes up. Also the
+upstream repository doesn't include this change. It is only (as far as I
+know) part of the raspberrypi deb repository with the following
+changelog:
+
+firmware-nonfree (1:20190114-1+rpt2) buster; urgency=medium
+  * Update brcmfmac43455-sdio.txt
+    - Update boardflags3
+ -- Serge Schneider <serge@raspberrypi.org>  Thu, 18 Apr 2019 14:35:34
++0100
+
+Upstream-status: Pending
+Signed-off-by: Andrei Gherzan <andrei@gherzan.ro>
+---
+ brcm/brcmfmac43455-sdio.txt | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/brcm/brcmfmac43455-sdio.txt b/brcm/brcmfmac43455-sdio.txt
+index 54d9321..6801286 100644
+--- a/brcm/brcmfmac43455-sdio.txt
++++ b/brcm/brcmfmac43455-sdio.txt
+@@ -21,7 +21,7 @@ btc_mode=1
+ #            bit1 for btcoex
+ boardflags=0x00480201
+ boardflags2=0x40800000
+-boardflags3=0x48200100
++boardflags3=0x44200100
+ phycal_tempdelta=15
+ rxchain=1
+ txchain=1
+-- 
+2.17.1
+

recipes-kernel/linux-firmware-rpidistro/linux-firmware-rpidistro_git.bb

@@ -33,7 +33,10 @@ LIC_FILES_CHKSUM = "\
 NO_GENERIC_LICENSE[Firmware-broadcom_bcm43xx-rpidistro] = "LICENCE.broadcom_bcm43xx"
 NO_GENERIC_LICENSE[WHENCE] = "WHENCE"
 
-SRC_URI = "git://github.com/RPi-Distro/firmware-nonfree"
+SRC_URI = " \
+    git://github.com/RPi-Distro/firmware-nonfree \
+    file://0001-brcmfmac43455-sdio.txt-Follow-raspbian-change-for-bo.patch \
+    "
 SRCREV = "b518de45ced519e8f7a499f4778100173402ae43"
 PV = "0.0+git${SRCPV}"
 
@@ -43,6 +46,13 @@ inherit allarch
 
 CLEANBROKEN = "1"
 
+do_unpack_append() {
+    bb.build.exec_func('do_clean_pc', d)
+}
+do_clean_pc() {
+    rm -rf ${S}/.pc
+}
+
 do_compile() {
     :
 }