ppp: Move to openwrt_core and update for new PPP version

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commit d5490166d55c29c6ccb3700d6919b7cdb3449f66 (HEAD -> agnau-move-ppp-to-openwrt-core, origin/agnau-move-ppp-to-openwrt-core) ┃
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Author: Andreas Gnau <andreas.gnau@iopsys.eu>
Date:   Thu Jul 7 11:06:14 2022 +0200

    ppp: Adapt BCM PPPoATM patch to PPP 2.4.9
    
    Adapt BCM PPPoATM patch to PPP 2.4.9 based on newest BCM SDK which has
    also switched to 2.4.9.
    
    Signed-off-by: Andreas Gnau <andreas.gnau@iopsys.eu>

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commit 0de16938ec1d4f0cbc47451953dfc4832b446a58 ┃
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Author: Andreas Gnau <andreas.gnau@iopsys.eu>
Date:   Wed Jan 26 19:45:04 2022 +0100

    ppp: Add target-specific patch for PPPoATM on BCM
    
    Add patch to PPPoATM plugin to make PPPoATM work on Broadcom platforms.
    The patch is based on what Broadcom does in their bcm963xx SDK version
    5.04L.02p1 at
       userspace/gpl/apps/ppp/ppp-2.4.8/pppd/plugins/pppoatm/pppoatm.c
    compared to vanilla upstream ppp-2.4.8.
    
    It makes PPPoATM work on Broadcom platforms and is only applied when
    compiling for the iopsys-brcm63xx-arm target.
    
    Signed-off-by: Andreas Gnau <andreas.gnau@iopsys.eu>

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commit 457f2903dd86f198a081447d00f0792b3f2e56f5 ┃
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Author: Sukru Senli <sukru.senli@iopsys.eu>
Date:   Wed Jan 26 13:35:10 2022 +0100

    ppp: process atmdev option as string
    
    On Broadcom platform atm device has format of atmX

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commit 2d04e2bc3aa56af3b45ebee8a3996606e1000a69 ┃
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Author: jjoseph <jomily.joseph@iopsys.eu>
Date:   Tue Aug 24 11:59:08 2021 +0530

    ppp : Add support for missing Device.PPP.Interface.{i}. parameters

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commit 968a19d83eda9a934f38a02fd4162fbf5a819b2e ┃
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Author: Jani Juvan <jani.juvan@iopsys.eu>
Date:   Mon Mar 1 13:50:32 2021 +0100

    ppp: add ppp scripts to install script

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commit 2df930c1ffb5e3d124148d5ea73cdf2590b132f1 ┃
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Author: Jani Juvan <jani.juvan@iopsys.eu>
Date:   Thu Feb 18 12:10:48 2021 +0100

    ppp: adding remote link local address to ubus data for Device.PPP.Interface.{i}.IPv6CP.RemoteInterfaceIdentifier