[PATCH] USB: sisusbvga: possible cleanups

This patch contains the following possible cleanups:
- make needlessly global functions static
- function and struct declarations belong into header files
- make SiS_VCLKData const
- #if 0 the following unused global functions:
  - sisusb.c: sisusb_writew()
  - sisusb.c: sisusb_readw()
  - sisusb_init.c: SiSUSB_GetModeID()

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>