Documentation: HID: amd-sfh-hid editing & corrections

Do basic editing & correction to amd-sfh-hid.rst:
- fix punctuation
- use HID instead of hid consistently
- fix grammar, verb tense
- fix Block Diagram heading

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: linux-input@vger.kernel.org
Cc: linux-iio@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>