tools/mkkconfig: mkkconfig not to complaining

tools/mkkconfig: mkkconfig not to complaining

mkkconfig.sh is a script for generating Kconfig recursively. Sometimes
it spits a trivial warning that is very annoying to see as following:

    mkkconfig in /home/heesub/Documents/artik053/tinyara/apps/netutils
    mkkconfig in /home/heesub/Documents/artik053/tinyara/apps/netutils
    ls: cannot access '/home/heesub/Documents/artik053/tinyara/apps/netutils/*/Kconfig_ENTRY': No such file or directory

This commit should stop mkkconfig.sh from complaining and will hopefully
save someone from having to debug it.

Change-Id: Iaef3cb00cc011d09d1d4abeda430dc16a56ddf83
Signed-off-by: Heesub Shin <heesub.shin@samsung.com>