libubi: Use global mtd_all_ff function ...

We introduced a global function for this, so use it.

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 libscan ...

Imported from mtd-utils and stripped down to needed functionality.
Add prefix to functions so we have a clean namespace.

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