usb: gadget: f_hid: fix: Move IN request allocation to set_alt()

Since commit: ba1582f2 ("usb: gadget: f_hid: use alloc_ep_req()")
we cannot allocate any requests in bind() as we check if we should
align request buffer based on endpoint descriptor which is assigned
in set_alt().

Allocating request in bind() function causes a NULL pointer
dereference.

This commit moves allocation of IN request from bind() to set_alt()
to prevent this issue.

Fixes: ba1582f2 ("usb: gadget: f_hid: use alloc_ep_req()")
Cc: stable@vger.kernel.org
Tested-by: David Lechner <david@lechnology.com>
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>