libcamera: Fix spellings and grammar

Fix a number of spelling errors and word duplications throughout the comments
within libcamera.

These were picked up with spellintian.

Also one capitalisation of the first word of a \return statement picked
up by checkstyle.py while creating this patch.

Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/ipa_module.cpp

@@ -348,7 +348,7 @@ close:
  * the IPA module information it contains was successfully retrieved and
  * validated.
  *
- * \return true if the the IPAModule is valid, false otherwise
+ * \return True if the IPAModule is valid, false otherwise
  */
 bool IPAModule::isValid() const
 {