Remove redundant dollar signs in Config.in files

Some Config.in(.host) files have constructs like:

config FOO_VERSION
	string
	default "1.0" if FOO_1_0
	default "2.0" if FOO_2_0
	default $FOO_CUSTOM_VERSION if FOO_CUSTOM

The dollar sign here is not needed and confusing, so can be removed.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>