fix warning on const constraint
../../src/wsfb_driver.c: In function 'WsfbPreInit':
../../src/wsfb_driver.c:574:9: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
574 | if ((s = xf86GetOptValString(fPtr->Options, OPTION_ROTATE))) {
| ^
Signed-off-by: Enrico Weigelt, metux IT consult info@metux.net
Edited by Alan Coopersmith