Check my node with is_for_session parameter

Check my node with is_for_session parameter

An error can occur when registering a focus node via sound-manager
if there already exists a node with the same index of the same process.
Because a node which is requested by sound-manager uses pulseaudio context id
whereas an internal focus node for session backward compatibility uses index
counted by focus_server itself.
This patch distinguishes both cases and ensures normal operation in this case.

[Version] 0.10.69
[Profile] Common
[Issue Type] Bug fix

Change-Id: Icbc9ec96940ea42bdb5cafa8d849f5cd767cc03c
Signed-off-by: Sangchul Lee <sc11.lee@samsung.com>