OMAP2 SDRC: add timing data for Micron MT46H32M32LF-6

Add timing data for the Micron MT46H32M32LF-6 SDRAM chip, used on the
OMAP3 Beagle and EVM boards.  Original timing data is from the Micron
datasheet PDF downloaded from:

http://download.micron.com/pdf/datasheets/dram/mobile/1gb_ddr_mobile_sdram_t48m.pdf

Thanks to Rajendra Nayak <rnayak@ti.com> for his help identifying
the chips used on Beagle & OMAP3EVM.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>