pitft: Add basic support for PiTFT

Add basic support for PiTFT display by using device-trees.

In order get it working below configurations must be active in
local.conf:

MACHINE_FEATURES += "pitft"
 - This will enable SPI bus and i2c device-trees, it will also setup
   framebuffer for console and x server on PiTFT.

[Support #70]

Signed-off-by: Petter Mabäcker <petter@technux.se>
Signed-off-by: Andrei Gherzan <andrei@gherzan.ro>

recipes-kernel/linux/linux-raspberrypi.inc

@@ -53,7 +53,11 @@ do_install_prepend() {
 do_deploy_append() {
     # Deploy cmdline.txt
     install -d ${DEPLOYDIR}/bcm2835-bootfiles
-    echo "${CMDLINE}" > ${DEPLOYDIR}/bcm2835-bootfiles/cmdline.txt
+    PITFT="${@bb.utils.contains("MACHINE_FEATURES", "pitft", "1", "0", d)}"
+    if [ ${PITFT} = "1" ]; then
+        PITFT_PARAMS="fbcon=map:10 fbcon=font:VGA8x8"
+    fi
+    echo "${CMDLINE}${PITFT_PARAMS}" > ${DEPLOYDIR}/bcm2835-bootfiles/cmdline.txt
 }
 
 do_rpiboot_mkimage() {