ARM: dts: msm: remove rot_clk_src for sdm845

The rotator's rot_clk_src is no longer used, so remove
its entries from the sdm845 target.

CRs-Fixed: 2040987
Change-Id: Ie1fba4d83cdeed7a30b3a0122eae2188c22b2fb9
Signed-off-by: Clarence Ip <cip@codeaurora.org>