ddr: add LPDDR2 data from JESD209-2

add LPDDR2 data from the JEDEC spec JESD209-2. The data
includes:

1. Addressing information for LPDDR2 memories of different
   densities and types(S2/S4)
2. AC timing data.

This data will useful for memory controller device drivers.
Right now this is used by the TI EMIF SDRAM controller
driver.

Signed-off-by: Aneesh V <aneesh@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Benoit Cousson <b-cousson@ti.com>
[santosh.shilimkar@ti.com: Moved to drivers/memory from drivers/misc]
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>