usb-misc: sisusbvga: Fix coding style: braces, parenthesis, comment

The file drivers/usb/misc/sisusbvga/sisusb.c contained coding style
issues reported by checkpatch. This patch fixes the following
errors:
 - 12 WARNING: braces {} are not necessary for single statement blocks
 - 04 ERROR: return is not a function, parentheses are not required
 - 03 ERROR: do not initialise statics to 0
 - 1 WARNING: else is not generally useful after a break or return
 - 1 WARNING: braces {} are not necessary for any arm of this statement
 - 1 WARNING: Block comments use * on subsequent lines

One case in which braces are not necessary is left unchanged as other
patch of the series will fix it.

Signed-off-by: Peter Senna Tschudin <peter.senna@collabora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>