tegra-alt: adsp: use nvadsp_mbox_send() for mailbox send

tegra-alt: adsp: use nvadsp_mbox_send() for mailbox send

Use nvadsp_mbox_send() to send mailbox message. This allows
blocking functionality with time out when sending messages.

Add runtime PM get/put when sending APM messages from widget
events as it was seen that this function is called even when
runtime resume had failed in one of the error cases.

Bug 200123443

Change-Id: I29e0860eadc73af2f32af58c1ca614806741709b
Signed-off-by: Viraj Karandikar <vkarandikar@nvidia.com>
Reviewed-on: http://git-master/r/779898
(cherry picked from commit 7cb1c2b7b51010ab97e4125825f4658b32479487)
Reviewed-on: http://git-master/r/785351
Reviewed-by: Sumit Bhattacharya <sumitb@nvidia.com>