soc: qcom: glink: Move get reference to valid location

In function ch_name_to_ch_ctx_create reference for ctx is taken
without checking if ctx is valid. This leads to possible NULL pointer
dereference.

Take reference only when it is verified that ctx is not NULL.

CRs-Fixed: 2059742
Change-Id: I15998780b602e325a90e7c8c303cd442c5381fe8
Signed-off-by: Dhoat Harpal <hdhoat@codeaurora.org>