lsmem: add --split

lsmem: add --split

Now the way how lsmem lists memory ranges is affected by used output
columns.  It makes it very difficult to use in scripts where you want
to use for example only one column

	ranges=$(lsmem -oRANGE)

and in this case all is merged to the one (or two) huge ranges and all
attributes are ignored. The --split allows to control this behavior

	ranges=$(lsmem -oRANGE --split=STATE,ZONES)

forces lsmem to list ranges by STATE and ZONES differences.

Signed-off-by: Karel Zak <kzak@redhat.com>