x86: switch to kernel 5.10

Seems to be working fine in QEMU and the wild.

Signed-off-by: Paul Spooren <mail@aparcar.org>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>

target/linux/x86/Makefile

@@ -10,8 +10,7 @@ BOARDNAME:=x86
 FEATURES:=squashfs ext4 vdi vmdk pcmcia targz fpu boot-part rootfs-part
 SUBTARGETS:=generic legacy geode 64
 
-KERNEL_PATCHVER:=5.4
-KERNEL_TESTING_PATCHVER:=5.10
+KERNEL_PATCHVER:=5.10
 
 KERNELNAME:=bzImage