HID: remove superfluous (and wrong) Makefile entry for CONFIG_INTEL_ISH_FIRMWARE_DOWNLOADER

The line

	obj-$(INTEL_ISH_FIRMWARE_DOWNLOADER)   += intel-ish-hid/

in top-level HID Makefile is both superfluous (as CONFIG_INTEL_ISH_FIRMWARE_DOWNLOADER
depends on CONFIG_INTEL_ISH_HID, which contains intel-ish-hid/ already) and wrong (as it's
missing the CONFIG_ prefix).

Just remove it.

Fixes: 91b22810 ("HID: intel-ish-hid: ISH firmware loader client driver")
Reported-by: Jiri Slaby <jirislaby@kernel.org>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>