artik053: sidk_s5jt200: fix warning messages when building

artik053: sidk_s5jt200: fix warning messages when building

DEPPATH needs to point to $(TOPDIR)/arch in order to build Make.dep
properly. This suppresses following build errors:

    make[1]: Entering directory '/home/heesub/Documents/artik053/tizenrt/os/arch/arm/src'
    make[2]: Entering directory '/home/heesub/Documents/artik053/tizenrt/os/arch/arm/src/artik053/src'
    Makefile:104: recipe for target '.depend' failed
    make[2]: *** [.depend] Error 1
    make[2]: Leaving directory '/home/heesub/Documents/artik053/tizenrt/os/arch/arm/src/artik053/src'
    Makefile:215: recipe for target '.depend' failed
    make[1]: *** [.depend] Error 2

Change-Id: I96feda1a095eb8d47feb17fcd1ccf56cffd84410
Signed-off-by: Heesub Shin <heesub.shin@samsung.com>