hid_generic_init() depends on hid_init() to init hid_bus_type.
But hid_generic_init() and hid_init() are both in the same
module_init level.
Fix this by moving hid_init() to the rootfs_initcall level.
Change-Id: I070f92c405d898ae9f929bff968a6bd26811085a
Signed-off-by: Tao Huang <huangtao@rock-chips.com>