Add a new power HAL

This very simple power HAL pins the L3 (memory) bus clock speed to the
max only while the screen is on, allowing us to benefit from improved
graphics performance without using power unnecessarily while the screen
is off.

Change-Id: Ib9f65fdd98e7dcec679f5a13878ff6033674fdb2
Remove obsolete/unused blobs

* DSP firmware: we're using newer firmware in the vendor/ tree
* overlay.omap3.so: obsolete since ICS

Change-Id: I0643f6cf4d175379d287bff87c8c0bbc43a63c2d
setup-makefiles.sh: remove obsolete libaudiopolicy.so reference

Change-Id: I2363b247838e1183c3fb8533e79ec70ff37d49b1
SurfaceFlinger: use HAS_CONTEXT_PRIORITY

The OMAP3 SGX530 EGL driver has this extension, and it appears to help
performance, so use it.

Change-Id: I5019674a3199e1efa69ccf57c8f860abdab645f9
Disable scissor optimization in the display stack

XXX: The scissor optimization is known to slow down SGX540; verify that
it slows down SGX530 as well

Change-Id: Ie1873456e755a745dbdffee941ece62eaacbca27