HID: intel_ish-hid: Stop using a static local buffer in get_report()

hid_ishtp_get_report() may be called by multiple callers at the same
time, causing trouble with the static local buffer used.

Also there is no reason to use a non stack buffer, the buffer is tiny
and ishtp_cl_send() copies its contents so the lifetime is not an
issue either.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>