ARM: dts: msm: Add MSM8909 QSIP volume up key support

MSM8909 QSIP volume up gpio key is connected to GPIO 91. Add
definition for GPIO 91.

CRs-Fixed: 1058742
Change-Id: I65ed76e0f728dae411feaae8196cb82b1ac4db78
Signed-off-by: Jin Fu <jinf@codeaurora.org>
Signed-off-by: Changmin Liu <changmil@codeaurora.org>