TWRP support

Change-Id: Ia74317f28f94e6b7af7d9ba538ed6ba874d5c065
Remove vendor references

They're now called from the common device tree.

Change-Id: Ia73cc5c715012138fa8dfb2dd6b586569f0b3b79
Omni bringup

Change-Id: Ib9c990fc06af529feb58d8cc90730e7f64931e84
Use the generic defconfig

Change-Id: I5a278f4e0c6501c36bf545125f4645bf883c9244
Misc makefile cleanups

Change-Id: Ibe231f8b4f84ff7872df5a1d8d85e7db62a30fa4