HID: Use Kbuild idiom in Makefiles

Use <driver>-$(CONFIG_FOO) syntax to build multipart objects with
optional parts, since all the config options are bool. Also, delete the
obvious comments in the usbhid Makefile.

Signed-off-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>