drivers: sensor: tdk: Refactor cmake and kconfig to vendor subdirectory

Refactors the cmake and kconfig bits of the tdk sensor drivers into the
vendor subdirectory to make them consistent with other vendor-sorted
sensor drivers. The tdk driver implementations were previously moved
into the vendor subdirectory in commit
41f1c3a2.

Signed-off-by: Maureen Helm <maureen.helm@analog.com>