rpmsg: align code with open parenthesis

This patch fixes most of the existing alignment checkpatch check
warnings of the type "Alignment should match open parenthesis"
in the virtio rpmsg bus code. A couple of them have been left as
is to not exceed the 80-char limit.

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