Fix the name of the constant for device [dis]connect parameter

During the transition to Treble, "device connect" / "disconnect"
parameter was erroneously attributed to audio streams. This
issue got fixed in Audio HAL V4.0, but AudioParameter file
was still using incorrect name for the constant.

Test: make
Change-Id: I18e1e3fccad3d41372f3c5c046af4f6ffd83328b
Merged-In: I18e1e3fccad3d41372f3c5c046af4f6ffd83328b