ddr: altera: Clean up rw_mgr_mem_calibrate_vfifo_center() part 9

The read_group and write_group arguments are the same in all
cases when this function is invoked, just merge them into one
rw_group argument. Also, clean up the function argument data
types and constify them.

Signed-off-by: Marek Vasut <marex@denx.de>
1 file changed