SystemUI: Improve HeadsUp expanding performance.

Change-Id: Ifd31caca6d2eb2432772b6a63f6b545f8288f449
HOVER: Respect screen limits when adding view

As for what @Decad3nce reported here http://review.cyanogenmod.org/#/c/66654/
we shouldn't keep FLAG_LAYOUT_NO_LIMITS so view doesn't exceed the screen limits.

Thank you Adnan :)

Signed-off-by: Carlo Savignano <stevewatersy@gmail.com>
Change-Id: Ifcbc4a1143362e1b7dd40e710126060688c894b9