staging/xgifb: Use TVCLKBASE_315 as a base address

Since the defines TVVCLKDIV2, TVVCLK, HiTVVCLKDIV2, HiTVVCLK,
HiTVSimuVCLK and HiTVTextVCLK are now defined as relative values, we
have to use TVCLKBASE_315 (0x31) as a base address to get the same values
as before the merge.

The old and now duplicated defines were removed

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