mxs: Rename CONFIG_SPL_MX28_PSWITCH_WAIT to CONFIG_SPL_MXS_PSWITCH_WAIT

The power switch option is compatible with i.MX23 and i.MX28 so the
configration option needs to reflect it. We choose
'CONFIG_SPL_MXS_PSWITCH_WAIT' for the option name.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Acked-by: Marek Vasut <marex@denx.de>
2 files changed