Fix feature image in Eclipse About window

In Feature set branding plugin to Elf32. Elf32 already has info required for ARC
image to be shown in Eclipse Abount Window.

Also set in Feature, that GDB plugin shouldn't be unpacked, like Elf32 plugin. I
don't have preference to any way, but they should be unified.

Signed-off-by: Anton Kolesov <anton.kolesov@synopsys.com>