pinctrl: qcom: Remove show_resume_irq support

The generic irq layer supports showing the resume irq via
/sys/power/pm_wakeup_irq as of commit a6f5f0dd ("PM / sleep:
Report interrupt that caused system wakeup"). Remove the custom
code here that duplicates that code.

Change-Id: Ic595be47453cfea92b9026142799fde458bd6cde
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>
Signed-off-by: Lina Iyer <ilina@codeaurora.org>
[Changes to apply on top of the 4.14 kernel]