recovery: init backgroundIcon properly to avoid recovery mode crash

We met factory issue that some devices would crash in recovery mode
because the backgroundIcon array did not reset to NULL when initializing.

Bug: 9568624
Change-Id: I13c7a7cc1053a7ffdbadd71740c1a2b4a2af6bba
Signed-off-by: yetta_wu <yetta_wu@asus.com>
Signed-off-by: Iliyan Malchev <malchev@google.com>