rpmsg: smd: Switch to SPDX license identifier

Use the appropriate SPDX license identifier in the rpmsg SMD backend
driver source file and drop the previous boilerplate license text.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
1 file changed