ARM: dts: msm: Use debug_mux_8937 as a measure clock for 8937

We are failed to get measure clock for 8937 target because of
this failure, we are not able to dumps pronto and iris register
dumps when we inject SSR.
measure clock get failed because we used clk_gcc_debug_mux as a
measure clock instead of clk_gcc_debug_mux_8937 for 8937 target.

CRs-Fixed: 955823
Change-Id: I63977ae28ae4e3917e8a5be6dcab68d7627dec06
Signed-off-by: Sunkad, Anand Ningappa <asunka@codeaurora.org>