If we have multiple instances of hid function, each of
them may have different report descriptor, also their
length may be different.

Currently we are using static hidg_desc varable which
is being filled in hidg_bind(). Then we send its content
to host in hidg_setup() function. This content may
have been already overwriten if another instance
has executed hidg_bind().
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>