package/xvisor: fix build with gcc 11

package/xvisor: fix build with gcc 11

Fix the following build failures with gcc 11:

/home/buildroot/autobuild/instance-3/output-1/host/lib/gcc/arm-buildroot-linux-gnueabihf/11.1.0/../../../../arm-buildroot-linux-gnueabihf/bin/ld: /home/buildroot/autobuild/instance-3/output-1/build/xvisor-0.3.0/build/drivers/drivers.o: in function `psmouse_extensions':
/home/buildroot/autobuild/instance-3/output-1/build/xvisor-0.3.0/drivers/input/mouse/psmouse-base.c:783: undefined reference to `lifebook_detect'
/home/buildroot/autobuild/instance-3/output-1/host/lib/gcc/arm-buildroot-linux-gnueabihf/11.1.0/../../../../arm-buildroot-linux-gnueabihf/bin/ld: /home/buildroot/autobuild/instance-3/output-1/build/xvisor-0.3.0/drivers/input/mouse/psmouse-base.c:783: undefined reference to `alps_detect'
/home/buildroot/autobuild/instance-3/output-1/host/lib/gcc/arm-buildroot-linux-gnueabihf/11.1.0/../../../../arm-buildroot-linux-gnueabihf/bin/ld: /home/buildroot/autobuild/instance-3/output-1/build/xvisor-0.3.0/drivers/input/mouse/psmouse-base.c:783: undefined reference to `ps2pp_init'
/home/buildroot/autobuild/instance-3/output-1/host/lib/gcc/arm-buildroot-linux-gnueabihf/11.1.0/../../../../arm-buildroot-linux-gnueabihf/bin/ld: /home/buildroot/autobuild/instance-3/output-1/build/xvisor-0.3.0/drivers/input/mouse/psmouse-base.c:783: undefined reference to `trackpoint_detect'
/home/buildroot/autobuild/instance-3/output-1/host/lib/gcc/arm-buildroot-linux-gnueabihf/11.1.0/../../../../arm-buildroot-linux-gnueabihf/bin/ld: /home/buildroot/autobuild/instance-3/output-1/build/xvisor-0.3.0/drivers/input/mouse/psmouse-base.c:783: undefined reference to `fsp_detect'

Fixes:
 - http://autobuild.buildroot.org/results/69062b9c80567d135edd48890165e69881cf7295

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>