mtd: Update internal API to support 64-bit device size ...

MTD internal API presently uses 32-bit values to represent device
size. This patch updates them to 64-bits but leaves the external API
unchanged.

In general, changing from 32-bit to 64-bit values cause little
or no changes to the majority of the code with the following
exceptions:
  - printk message formats;
  - division and modulus of 64-bit values (mtd_div_by_wb,
    mtd_div_by_eb may be used in some of such cases).

Was tested on phyFLEX i.MX6.

Signed-off-by: Dmitry Lavnikevich <d.lavnikevich@sam-solutions.com>
Signed-off-by: Grigory Milev <g.milev@sam-solutions.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

mtd: Add subpagesize to mtd_info_user ...

ubiformat needs the subpagesize to work correctly. The kernel uses
sysfs to pass the subpagesize, but in barebox we have the possibility
to extend struct mtd_info_user. Add a corresponding field and use it
in ubiformat.

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

libmtd: rename functions from mtd_* to libmtd_* ...

The kernel nowadays has mtd_read/write and other functions. In
barebox we also have these functions, but with a different prototype,
namely they correspond to the libmtd userspace functions. Rename
these functions to libmtd_* to avoid name clashes with future mtd
updates.

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

lib: add barebox version of libmtd ...

Based on mtd-utils and stripped down to needed functionality and
reworked to barebox interfaces.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>