configs: Add missing TOUCHSCREEN_RASPBERRYPI_FW=m

The 32- and 64-bit bcm2711 defconfigs are missing support for the
official Raspberry Pi touchscreen.

Restore the missing config settings.

See: https://github.com/Hexxeh/rpi-firmware/issues/223



Signed-off-by: Phil Elwell <phil@raspberrypi.com>