arm64: dts: sprd: Removed unused clock references from etm nodes

Remove these unused clock references to fix dtbs_check warnings:

etm@3f740000: clocks: [[11], [35, 34], [36, 8]] is too long
etm@3f740000: clock-names:1: 'atclk' was expected
etm@3f740000: clock-names: ['apb_pclk', 'clk_cs', 'cs_src'] is too long

Link: https://lore.kernel.org/r/20231221092824.1169453-1-chunyan.zhang@unisoc.com


Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>