drivers: qcom: mpm: Use GIC fwspec translation for MPM-GIC

Client drivers request GIC interrupt number which needs to be
translated to hwirq so that right MPM pin can be retrieved.

Change-Id: Ib952c94da9889df9757c7ba224e4655e478dacca
Signed-off-by: Raghavendra Kakarla <rkakarla@codeaurora.org>