ARM: MXS: allow configuration of EMI clock prescaler ...

Allow to set not only the fractional divider, but also the prescaler for
the EMI clock in mxs_mem_init_clock(), and rename the parameters
accordingly to reflect the change. Port the existing board code to set
up the EMI clock explicitely with the old values. Also fix the
off-by-a-half error in the comments, which did not take the prescaler of
2 into account, on which the fractional divider is applied (according to
the i.MX23/i.MX28 Reference Manuals)

Signed-off-by: Roland Hieber <r.hieber@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: MXS: i.MX28: allow setup of low-voltage SDRAM ...

The PINCTRL_*_DDR_MODE_* defines are now needed in global scope, so move
them to the respective include header.

Signed-off-by: Roland Hieber <r.hieber@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: mxs: add parameter to mx28_mem_init to allow custom memory config ...

Rename the already global array of default memory settings to make the
intended usage more obvious.

Also make generous use of the const keyword.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: MXS: Setup vdda in power prep ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: mxs: Add lowlevel setup from U-Boot ...

U-Boot has code to replace the infamous Freescale bootlet code.
This patch adds this for barebox with some changes:
- Separate it more into mx23/mx28 functions instead of mxs functions
  with #ifdefs for the actual SoC
- Add mx2x_power_init_battery_input() power entry point for boards
  which have a regulated input on the battery pin to supply the board.
- Export more functions to be more flexible when boards need non standard
  setup.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>