soc: qcom: glink: Fix ctx initialization with magic number

Glink channel context is initialized with magic number after sending
open command to remote side.

Initialization is fixed and happen before sending open command.

CRs-Fixed: 1075481
Change-Id: Ia6b28a3b35a4093aea7af1cffea2a5e093d33ccd
Signed-off-by: Dhoat Harpal <hdhoat@codeaurora.org>