IconPackHelper:Use un-tinted iconback when no defaultSwatchcolor is specified

After applying the theme which supports paletteback feature and if there is
no defaultSwatchColor specified then the background should go to the
original color. Instead in a particular FootballDemo theme the theme
would never get applied and just flood the logcat with null exceptions
for each and every app.

RM-290

Change-Id: If2bd3d23ab5075dac1d8ff3f197cebc28c9c1f20
(cherry picked from commit 4910bb1c)