convert some images from png to svg

SVG images are nicer, as they can easily be scaled. Also, they're
written in text, with makes easier to work.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/media/uapi/dvb/intro.rst

@@ -56,7 +56,7 @@ Overview
 .. _stb_components:
 
 .. figure::  intro_files/dvbstb.*
-    :alt:    dvbstb.pdf / dvbstb.png
+    :alt:    dvbstb.pdf / dvbstb.svg
     :align:  center
 
     Components of a DVB card/STB

Documentation/media/uapi/v4l/vidioc-g-selection.rst

@@ -130,7 +130,7 @@ Selection targets and flags are documented in
 .. _sel-const-adjust:
 
 .. figure::  vidioc-g-selection_files/constraints.*
-    :alt:    constraints.png
+    :alt:    constraints.svg
     :align:  center
 
     Size adjustments with constraint flags.