ddr: marvell: update additional ODT setting

The RD_SAMPLE_DELAY field is 5 bits so it needs to be masked with 0x1f
instead of 0xf. Rather than checking the read sample delay for all DDR
chip selects use the values for the chip selects that are actually
configured. Finally continue searching for the max_phase value even if the
current read_sample is the same as the max_read_sample.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Signed-off-by: Stefan Roese <sr@denx.de>