trx: factor out clock indication handling into helper
Extract clock indication handling logic into trx_clk_phy()
and reuse it from trx_clk_read_cb()
This separates core FN processing from socket-specific code
and prepares for alternative clock sources
No functional changes intended
Change-Id: I0e6b3e25da14ada4d0ef86fd4c4e6bbc12e447d2
