pkg: Update kernel used for the firmware package
# Make modules from a recentish kernel available
-FROM linuxkit/kernel:4.14.12 AS kernel
+FROM linuxkit/kernel:4.14.28 AS kernel
FROM linuxkit/alpine:96ad1eb5ec262b4cd0eef574cdc0b225b502d9ee AS build
RUN apk add --no-cache git kmod
