[openwrt/openwrt] Revert "mvebu: switch default kernel to 5.15"

[LEDE Commits]

ynezz pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/97c77fff28cf001399f33c7bc1ec6687ba18450b

commit 97c77fff28cf001399f33c7bc1ec6687ba18450b
Author: Petr Štetiar <ynezz at true.cz>
AuthorDate: Sun Dec 4 08:08:24 2022 +0100

    Revert "mvebu: switch default kernel to 5.15"
    
    This reverts commit 5429411f732ba76eced30b5b596ec9c0374d0965 as upstream
    in commit e5f31552674e ("ethernet: fix PTP_1588_CLOCK dependencies") has
    changed `PTP_1588_CLOCK` dependency handling in 5.15 kernel.
    
    That currently leads to `CONFIG_NET_DSA_MV88E6XXX=m` in images produced
    by buildbots due to `CONFIG_ALL_KMODS=y` config option being used in
    those builds, which leads to a broken LAN bridge network on several
    devices.
    
    References: https://lists.infradead.org/pipermail/openwrt-devel/2022-December/039950.html
    Signed-off-by: Petr Štetiar <ynezz at true.cz>
---
 target/linux/mvebu/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/target/linux/mvebu/Makefile b/target/linux/mvebu/Makefile
index 2971f3fcaf..6a1e0f63f7 100644
--- a/target/linux/mvebu/Makefile
+++ b/target/linux/mvebu/Makefile
@@ -9,7 +9,8 @@ BOARDNAME:=Marvell EBU Armada
 FEATURES:=fpu usb pci pcie gpio nand squashfs ramdisk boot-part rootfs-part legacy-sdcard targz
 SUBTARGETS:=cortexa9 cortexa53 cortexa72
 
-KERNEL_PATCHVER:=5.15
+KERNEL_PATCHVER:=5.10
+KERNEL_TESTING_PATCHVER:=5.15
 
 include $(INCLUDE_DIR)/target.mk