qcom: mpm-of: fix build error when msm TLMM isn't configured

Currently when none of msm TLMM pinctrl drivers is configured, mpm-of
driver tries to use irq extension from TLMM driver and results in build
error.  Fix mpm-of driver to refer to proper irq extension.

Also revise driver init function to avoid null pointer dereference
accordingly for the case irq extension is null accordingly.

Change-Id: I966d58ba2701d3c092b9aa8f425c28e51b4881f1
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>