hwtracing: Add HW tracing support menu

Make a "HW tracing support" menu and move 2 entries into it.
(No change in Coresight, which is ARM-specific and is only listed for
ARM & ARM64.)

This makes the Device Drivers menu more consistent and prevents these
drivers from being listed at the top level of the Device Drivers menu.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>