Add Makefile option to skip lining of helm charts

Add Makefile option to skip lining of helm charts

For some reason after introducing our awesome templates to ONAP make
command can take now quite a lot of time, which sometimes causes out
CI jobs to fail.

Command that takes so much time is helm lint.
This patch adds a Makefile option that allows you to skip linting of
helm charts and just build them. Example:

make SKIP_LINT=TRUE

Default behavior stays unchanged.

Issue-ID: OOM-2055
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Change-Id: Ic50bad0cc82892e1daecc5761d6144d788a79d9f