hid-debug.c: make local symbols static

The symbols hid_resolv_event and hid_dump_input_mapping
are only used locally in this file. Make them static to prevent
the following sparse warnings:

warning: symbol 'hid_resolv_event' was not declared. Should it be static?
warning: symbol 'hid_dump_input_mapping' was not declared. Should it be static?
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>