docs: driver.rst: supress two ReSt warnings

Get rid of those, by marking a literal block as such:

	Documentation/driver-api/gpio/driver.rst:425: WARNING: Unexpected indentation.
	Documentation/driver-api/gpio/driver.rst:423: WARNING: Inline emphasis start-string without end-string.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/8356b02547087979f57cb71fbefb5e5f636c78f4.1583250595.git.mchehab+huawei@kernel.org


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