kernel: Cleanup. Remove redundant test when calling _Swap()
kernel: Cleanup. Remove redundant test when calling _Swap()

_Swap() must already handle the case where _get_next_ready_thread() is
the same as _current.

Signed-off-by: Andy Ross <c70f9a6bf6ee0cd69c8af4ce5e6b131945769315@intel.com>

galak/zephyr,explora26/zephyr,explora26/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,ldts/zephyr,explora26/zephyr,ldts/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,ldts/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,finikorg/zephyr,ldts/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr