msm_fb: Increase the pixel clock range for DSI panels

Increase the upper limit for the pixel clock that
changed with the newer version of the DSI controller.

CRs-Fixed: 380003
Change-Id: Ibbeaa478b4d12ae8f350be41f959d53a6ae6c923
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>