rxvt-unicode: Fix icon name

There was no icon being displayed for this, fix the name so that
is corrected.

(From OE-Core rev: 3bf3d123e1c62d1811039328f1f557ae35dec3fd)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-sato/rxvt-unicode/rxvt-unicode/rxvt.desktop

@@ -3,7 +3,7 @@ Version=1.0
 Name=Terminal
 Comment=A unicode capable rxvt clone
 Exec=rxvt
-Icon=terminal
+Icon=utilities-terminal
 Terminal=false
 Type=Application
 Categories=Utility;TerminalEmulator;