features_check: Factorize code for checking features
The DISTRO/MACHINE/COMBINED features should be treated identically, so
convert the expanded code to a loop. This fixes some of the COMBINED error
messages which were previously referring to MACHINE features. There
should be no functional changes.
Signed-off-by: Jacob Kroon <jacob.kroon@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>