docs: staging/tee.rst: fix two typos found while reading

Signed-off-by: Wang Cheng <wanngchenng@gmail.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220115125236.34886-1-wanngchenng@gmail.com


Signed-off-by: Jonathan Corbet <corbet@lwn.net>