Revert "Modified the osd program_info  window to display the coveart by default or fall back to the channel icon"

This reverts commit 4b019c5e55ae1740afa17695f16d5a4f30acb0b9.
Modified the osd program_info  window to display the coveart by default or fall back to the channel icon
or if both are not available to fall back to the coverart xplace holder image. (take two)

new file:   images/osd/masks/osd_program_coverart_mask.png
modified:   images/osd/masks/osd_program_icon_mask.png
modified:   osd.xml
modified:   osd.xml.alt
Bumped version to 4.56.

modified:   themeinfo.xml