soc: xilinx: vcu: drop coreclk from struct xlnx_vcu

soc: xilinx: vcu: drop coreclk from struct xlnx_vcu

The coreclk field is newer read after being written to xlnx_vcu. Remove
the coreclk field from the xlnx_vcu and use a function local variable
instead.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/20210121071659.1226489-4-m.tretter@pengutronix.de
Signed-off-by: Stephen Boyd <sboyd@kernel.org>