samples: tickless: Enables tickless kernel option in some apps

Adds changes to enable existing kernel and timer tests and samples to
be used to test the tickless kernel feature.

Updated samples/philosophers and tests/kernel/timer/timer_api apps

Run the tests using following commands
make pristine && make BOARD=<board> CONF_FILE=prj_tickless.conf qemu
Board could be any of the following
qemu_x86
quark_se_c1000_devboard

Jira: ZEP-339 ZEP-1812
Change-Id: I1530b19b79ddeb0e2181594caf15f3ac28ff51f4
Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com>