Refactor kernel image creation to make upgrading easier

kernel.do → default.kernel.do

@@ -2,11 +2,11 @@
 >/dev/null command -v flex
 >/dev/null command -v bison
 
-redo-ifchange linux-5.7-rc6.tar.gz
-tar xzf linux-5.7-rc6.tar.gz
+redo-ifchange "${2}".tar.gz
+tar xzf "${2}".tar.gz
 
 REFORM_D=reform2-imx8mq
-LINUX_D=linux-5.7-rc6
+LINUX_D="${2}"
 
 export \
  ARCH=arm64 \

reform-system.img.do

-redo-ifchange kernel
+redo-ifchange linux-5.7-rc6.kernel
 
 PARTED="/sbin/parted"
 TRUNCATE="/usr/bin/truncate"