pinctrl: qcom: add null point derefernce check for irq_desc parent

Fix null point derefernce of parent_irq in removal of direct
connected tlmm pin's irq desc.

Change-Id: I6c236be1f1f001ab626d9b3d57df5a16a00eacd5
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>