rpmsg: glink: Add missing MODULE_LICENSE

commit 1e0d5615 upstream.

The qcom_glink_native driver is missing a MODULE_LICENSE(), correct
this.

Fixes: 835764dd ("rpmsg: glink: Move the common glink protocol implementation to glink_native.c")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>