Voicefile: remove < and > from voice strings before speaking.
Some language files have the < and > characters the original string (like "<All
tracks>") has included in the voice strings. These characters cause the
generated wave file to not contain any samples with SAPI, causing an error when
Rockbox Utility tries to encode the file.
Since those characters don't make much sense in the voice string remove them
prior to speaking. Currently affected languages are basque, chinese-simp, and
russian, for which this fixes voicefile creation.
Change-Id: Iac7ccd7921ccfb5ddc33645239a1f8f7e639e5aa