remove --with-tune=cortex-a9

This partially reverts this commit:
82cd29ba540cbc5cb397b073a99d4fde2adf39c4
Signed-off-by: Paul Beeler <sparksco@gmail.com>

Change-Id: Iccd7dc4fa07c0e1138b59bffb241a697cee12b3e
optimize for armv7-a
Signed-off-by: Paul Beeler <sparksco@gmail.com>

Change-Id: I7cea516e780b328378ceb8fbaf962458a857143d
Signed-off-by: Paul Beeler <sparksco@gmail.com>