Move ubi-utils libraries to common library location

Move ubi-utils libraries to common library location

Historically, the mtd-utils and ubi-utils were seperate packages. The
ubi-utils were at some point merged into the mtd-utils. They first
appeared in the release tar-ball in version 1.1.0 in their own
sub-hirarchy with their own buildsystem, readme, documentation, etc.
A lot of the duplicated stuff got centralized/removed over time.

This patch further cleans up the directory hirarchy duplication by
moving common libraries from the ubi-utils/ into the central lib/
and include/ directories in the top directory of the mtd-utils package.

This includes:
 - libuib.a & libubigen.a used by the ubi utilities
 - libscan.a currently only used by ubiformat
 - libiniparser.a used by ubinize

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>