id3v2: Support v2.2 PIC

id3 v2.2 uses image format ("JPG","PNG") instead of mimetypes.

Currently, the attached picture is skipped because the format string
does not match a known picture mimetype.

This patch fixes this behaviour.

Signed-off-by: Mohammad Alsaleh <msal@tormail.org>
Signed-off-by: Anton Khirnov <anton@khirnov.net>