ARM: OMAP2+: gpmc: Move legacy GPMC width setting

After the introduction of gpmc_set_legacy(), move the GPMC width setting
to be done inside it. Currently, in the DT probed case, this is (wrongly)
done twice: first at gpmc_read_settings_dt(), and then based in the
NAND width setting.
Fix this and use only the value obtained from the DT.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>