video: Allow querying the font size

All the font size to be queried using the 'font size' command.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/usage/cmd/font.rst b/doc/usage/cmd/font.rst
index a8782546..44a04f5 100644
--- a/doc/usage/cmd/font.rst
+++ b/doc/usage/cmd/font.rst
@@ -13,7 +13,7 @@
 
     font list
     font select <name> [<size>]
-    font size <size>
+    font size [<size>]
 
 Description
 -----------
@@ -34,7 +34,7 @@
 font size
 ~~~~~~~~~
 
-This changes the font size only.
+This changes the font size only. With no argument it shows the current size.
 
 Examples
 --------
@@ -44,6 +44,8 @@
     => font list
     nimbus_sans_l_regular
     cantoraone_regular
+    => font size
+    30
     => font size 40
     => font select cantoraone_regular 20
     =>