HID: intel-ish-hid: pci-ish: Remove unused variable 'ret'

Fixes the following W=1 kernel build warning(s):

 drivers/hid/intel-ish-hid/ipc/pci-ish.c: In function ‘ish_resume_handler’:
 drivers/hid/intel-ish-hid/ipc/pci-ish.c:264:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]

Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Zhang Lixu <lixu.zhang@intel.com>
Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc: Daniel Drubin <daniel.drubin@intel.com>
Cc: linux-input@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>