rpmsg: glink: Pass task structure to set_cpus_allowed_ptr

Passing in "current" would set the kworker's affinity rather
than the glink rx thread's affinity. Hence, pass in the task
structure to the glink rx thread when setting cpu affinity.

Change-Id: I95e88879ebaf68ce98132829c8b4cea9b8588750
Signed-off-by: Jay Jayanna <jayanna@codeaurora.org>