misc: Spelling and grammar fixes in comments

* it's -> its
* grammar fix in ui/vnc-enc-zywrle.h

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Don Koch <dkoch@verizon.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
1 file changed