Use cml1-config to configure kernels for systemd

Add new kernel-config-systemd bbclass which uses cml1-config to merge in
the systemd configuration.

Signed-off-by: Mikhail Durnev <mikhail_durnev@mentor.com>
Merge pull request #210 from mdurnev/mdurnev/systemd.cfg

Use cml1-config to configure kernels for systemd