HID: allocate hid_parser in a proper way

hid_parser is non-trivially large structure, so it should be allocated
using vmalloc() to avoid unsuccessful allocations when memory fragmentation
is too high.
This structue has a very short life, it's destroyed as soon as the report
descriptor has been completely parsed.

This should be considered a temporary solution, until the hid_parser is
rewritten to consume less memory during report descriptor parsing.

Acked-by: Mariusz Kozlowski <m.kozlowski@tuxland.pl>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>