HID: hyperv: match wait_for_completion_timeout return type

The return type of wait_for_completion_timeout is unsigned long not
int. This patch fixes up the declarations only.

Patch was compile tested only for x86_64_defconfig + CONFIG_X86_VSMP=y
CONFIG_HYPERV=m, CONFIG_HID_HYPERV_MOUSE=m

Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>