staging: fbtft: fix build error

while building on i386 it gives a build warning about msg undeclared.

Fixes: e6ffd1ba ("staging: fbtft: fix out of bound access")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>