Added 'host' device for various *_RUN_PLACEHOLDER because
SYCL_DEVICE_FILTER won't automatically add it.
Also fixed some bugs of HOST/CPU/ACC_RUN_PLACEHOLDERS.
They should not be prefixed with {SYCL_PLUGIN}: because
these invalid BE:DEV_TYPE combination will end up being no
device available.
Signed-off-by: Byoungro So <byoungro.so@intel.com>