package: unification of name <pkg>_VERSION_MINOR variable

Currently there are two different names of the minor version variable:
<PKG>_MINOR_VERSION and <PKG>_VERSION_MINOR
This patch unifies them to <PKG>_VERSION_MINOR

Signed-off-by: Jerzy Grzegorek <jerzy.grzegorek@trzebnica.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>