By default, enabling the HID Device service is only possible
during disabling the HID Host service. If, on the other hand,
the HID Host service was never initialized, then a request to
enable the HID Device service should just be executed
immediately.

Test: manual, on a device without the HID Host profile.
Change-Id: I2ab4b8aec413b66d57eb322d38660f1b4c48ba32