docs: power: Fix footnote reference for Toshiba Satellite P10-554

Sphinx reports unreferenced footnote warning on "Video issues with S3
resume" doc:

Documentation/power/video.rst:213: WARNING: Footnote [#] is not referenced. [ref.footnote]

Fix the warning by separating footnote reference for Toshiba Satellite
P10-554 by a space.

Fixes: 151f4e2 ("docs: power: convert docs to ReST and rename to *.rst")
Reported-by: Stephen Rothwell <[email protected]>
Closes: https://lore.kernel.org/linux-next/[email protected]/
Signed-off-by: Bagas Sanjaya <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: bagasme

Documentation/power/video.rst

@@ -190,7 +190,7 @@ Toshiba Portege 3020CT		s3_mode (3)
 Toshiba Satellite 4030CDT	s3_mode (3) (S1 also works OK)
 Toshiba Satellite 4080XCDT      s3_mode (3) (S1 also works OK)
 Toshiba Satellite 4090XCDT      ??? [#f1]_
-Toshiba Satellite P10-554       s3_bios,s3_mode (4)[#f3]_
+Toshiba Satellite P10-554       s3_bios,s3_mode (4) [#f3]_
 Toshiba M30                     (2) xor X with nvidia driver using internal AGP
 Uniwill 244IIO			??? [#f1]_
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