configs/artik05x: modify to chages platform value for windows
configs/artik05x: modify to chages platform value for windows

In windows, the platform value has slightly different for each
environment such as Windows native, msys, cygwin. This commit modifies
to use common value instead of platform variable

Change-Id: I84c2ea9de7819bf6a4e3496f0141bdeee9d914b1
Signed-off-by: Jihun Ahn <31fe625dd60d1475d1b18ea57157c450e67c870a@samsung.com>

JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT