p1-common: disable triple buffering

this flag can be used to disable triple buffering
on per target basis. On aries/crespo/p1 it is possible to do so in theory
to save memory, however, there are currently some limitations in the
OpenGL ES driver that in conjunction with disable triple-buffering
would hurt performance significantly (see b/6016711)

tested on p1 and it performance still acceptable
the main target is just saving memory at moment

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: Idbbc31d54846bb0586203a3578843103c833e1c4