Font fix since Doxygen is not shipping FreeSans anymore

src/doc/dox/src/os_templ/hw_templ/Doxyfile

@@ -1370,7 +1370,7 @@ HAVE_DOT               = NO
 # DOTFONTPATH environment variable or by setting DOT_FONTPATH to the directory
 # containing the font.
 
-DOT_FONTNAME           = FreeSans
+DOT_FONTNAME           = Helvetica
 
 # The DOT_FONTSIZE tag can be used to set the size of the font of dot graphs.
 # The default size is 10pt.

src/doc/prm/src/os_templ/hw_templ/Doxyfile

@@ -1464,7 +1464,7 @@ DOT_NUM_THREADS        = 0
 # DOTFONTPATH environment variable or by setting DOT_FONTPATH to the directory
 # containing the font.
 
-DOT_FONTNAME           = FreeSans
+DOT_FONTNAME           = Helvetica
 
 # The DOT_FONTSIZE tag can be used to set the size of the font of dot graphs.
 # The default size is 10pt.