README.md: update build instructions

Signed-off-by: Alin Jerpelea <alin.jerpelea@sonymobile.com>
Merge pull request #3 from xperia-aosp-project/master

Add sensor_def_qcomdev.conf
kernel update to commit 3294754a177e0f6c05147a294a32987dd9c9a5c9

Signed-off-by: Alin Jerpelea <alin.jerpelea@sonymobile.com>
Merge pull request #1 from sonyxperiadev/master

Master