Most i.MX6SL infrastructure is already covered in barebox by general i.MX6
support. Missing infrastructure provided in separate commits are
* SoC type detection
* Clock infrastructure

Add the missing fsl,imx6sl-mmdc, so it will not be catched by fsl,imx6q-mmdc
and the remaining bits and pieces to provide barebox i.MX6SL SoC support.

Signed-off-by: Alexander Kurz <akurz@blala.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

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

Taken from the kernel as of 4.10-rc3. Needed for i.MX7

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

Based on analogous code from Linux kernel

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Port imx_check_clocks() from Linux kernel.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Move clk code from 'mach-imx' to 'drivers' to keep the code tree
structure closer to that of analogous one from Linux kernel and,
arguably although subjective, to keep 'mach-imx' less cluttered.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>