fix "lxfb: extend PLL table to support dotclocks below 25 MHz"

The following patch caused a regression with OLPC panels:

 commit 3888d463


    lxfb: extend PLL table to support dotclocks below 25 MHz

    Extends the PLL frequency table of the AMD Geode-LX frame buffer driver to
    make use of the DIV4 bit, thus adding support for dotclocks between 6 and 25
    MHz.  These are needed for small LCDs (e.g.  320x240).  Also inserts some
    intermediate steps between pre-existing frequencies.

The problem was the insertion of intermediate steps into the frequency
table; they would cause the wrong frequency to be matched.  This patch
drops those intermediate frequencies while keeping the sub-25MHz
frequencies.

Signed-off-by: Andres Salomon <dilinger@debian.org>
Signed-off-by: Jens Rottmann <JRottmann@LiPPERT-AT.de>
Tested-by: Andres Salomon <dilinger@debian.org>
Acked-by: Jordan Crouse <jordan.crouse@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>