optimized LPDDR RAM timings (~10% throughput increase)

Tweaked the device's RAM timings. Benchmarks suggest a 10
percent thorughput improvement (RgBandwidth RAM misc benchmark;
threads: 1. 20 benchmark instances each, best result wins):

       Stock          Tweaked

Copy   1249.9 MB/s -> 1373.0 MB/s --> 9.86 % improvement
Scale  1084.8 MB/s -> 1188.1 MB/s --> 9.52 % improvement
Add    938.4 MB/s  -> 1050.2 MB/s --> 11.91 % improvement
Triad  923.0 MB/s  -> 1043.5 MB/s --> 13.06 % improvement

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
omap2: overclock ram.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>