Staging: xgifb: Fix quoted string split across lines in XGI_main_26.c

This patch fixes the following checkpatch.pl issues in XGI_main_26.c:
WARNING: Quoted string split across lines

Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>