The 'Purple_Glow_V3' theme uses the following
'UI viewport' setting which is missing a comma
after the viewport height:
ui viewport: 0,0,271,212-,-,-
The setting is actually ignored when loading this theme,
since a UI viewport is already defined in the supplied
SBS file.
Rockbox will crash, though, when and if the next theme
that is loaded resets the SBS by setting it to "-", but
doesn't adjust the UI viewport setting at the same time.
To fix, use default UI viewport when encountering fewer
parameters than expected for the UI viewport setting.
Change-Id: I2648565ac59369ce8ab18d8e84b7fa69ad767f25
2b30a9fed8