staging/xgifb: Remove unused values in XGI340_ECLKData

In the lookup table XGI340_ECLKData only the first three 'lines' are
used, thus the remaining entries can be removed.

Rationale:
- vb_init.c uses pVBInfo->ram_type as the index for XGI340_ECLKData.

- pVBInfo->ram_type is assigned the return value of
XGINew_GetXG20DRAMType which can only be 0, 1 or 2

-> only the first three values are used.
-> remove the remeining entries.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>