mtd: improve parameter parsing for block2mtd

Expand the parameter parsing for block2mtd.  It now accepts:
Ki, Mi, Gi	- the official prefixes for binary multiples,
		  see http://physics.nist.gov/cuu/Units/binary.html

,
ki		- mistake on my side and analog to "k" for decimal multiples,
KiB, MiB, GiB	- for people that prefer to add a "B" for byte,
kiB		- combination of the above.

There were complaints about not accepting "k" for 1024.  This has long
been common practice, but is known to lead to confusion.  Hence the new
SI units and hence block2mtd only accepts units that cannot be confused
with decimal units.  Diverging from common practice doesn't always please
people, even if the change is for the better.

Signed-off-by: Joern Engel <joern@wohnheim.fh-wedel.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>