poky-tiny: Switch to 4.18 kernels

(From meta-yocto rev: 2b2d41267bae85dc7bf85a3165c1a46781259000)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-poky/conf/distro/poky-tiny.conf

@@ -38,7 +38,7 @@ TCLIBC = "musl"
 # Distro config is evaluated after the machine config, so we have to explicitly
 # set the kernel provider to override a machine config.
 PREFERRED_PROVIDER_virtual/kernel = "linux-yocto-tiny"
-PREFERRED_VERSION_linux-yocto-tiny ?= "4.14%"
+PREFERRED_VERSION_linux-yocto-tiny ?= "4.18%"
 
 # We can use packagegroup-core-boot, but in the future we may need a new packagegroup-core-tiny
 #POKY_DEFAULT_EXTRA_RDEPENDS += "packagegroup-core-boot"