plugins/hotpages: introduce sortby arg and parsed bool args correctly

plugins/hotpages: introduce sortby arg and parsed bool args correctly

Since plugin arguments now expect boolean arguments, a plugin argument
name "sortby" now expects a value of "read", "write", or "address".

"io" arg is now expected to be passed as a full-form boolean parameter,
i.e. "io=on|true|yes|off|false|no"

Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210730135817.17816-4-ma.mandourr@gmail.com>