examples: add dependencies for timer and vm_power_manager
examples: add dependencies for timer and vm_power_manager

Do not compile these examples if the related dpdk option is not
enabled, as it's done for other examples. It allows to build
the examples directory with a reduced dpdk configuration.

Signed-off-by: Olivier Matz <dfcc1510895413197abb4336e39bb0a3906cba71@6wind.com>

venkynv/dpdk-mirror,tsphillips/dpdk-fork,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,msune/dpdk,mixja/dpdk,mixja/dpdk,mixja/dpdk,msune/dpdk,venkynv/dpdk-mirror,msune/dpdk,venkynv/dpdk-mirror,john-mcnamara-intel/dpdk,tsphillips/dpdk-fork,tsphillips/dpdk-fork,mixja/dpdk,msune/dpdk,venkynv/dpdk-mirror,tsphillips/dpdk-fork