classes/lib: Add expand parameter to getVarFlag

classes/lib: Add expand parameter to getVarFlag

This sets the scene for removing the default False for expansion
from getVarFlag. This would later allow True to become the default.

On the most part this is an automatic translation with:

sed -e 's:\(\.getVarFlag([^,()]*, [^,()]*\)):\1, True):g'  -i `grep -ril getVar *`

In this case, the default was False, but True was used since in most
cases here expansion would be expected.

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