Replace the Rockbox logo with an svg version. Since the file size (i.e.
the page size in the svg) that isn't intended for use as icon we need to
enable scaling, and since scaling the label content doesn't keep the
aspect ratio we need to explicitly set the desired values.
Notably improves representation on HiDPI monitors. Now only the player
icons are still raster images.
Change-Id: I03216391a4b0ac982b16f5bec2b48c073369a3f6
d148afca3b