ARM: dts: msm: fix the DT string for dynamic fps for 8939 SKUK

For NT35596 video mode panel on 8939 SKUK device, the dynamic
refresh rate DT string is incorrect. This causes display not to
come up during suspend/resume sometimes due to incorrect variable
refresh rate operations. Fix this issue by correcting the DT string
appropriately.

Change-Id: I28333df65ff9e0d967cb9c86618d040d4ac806e2
Signed-off-by: Anusha Koduru <kanusha@codeaurora.org>