driver/mtd:IFC NAND:Initialise internal SRAM before any write

IFC-1.1.0 uses 28nm techenology for SRAM. This tech has known limitaion for
SRAM i.e. "byte select" is not supported. Hence Read Modify Write is
implemented in IFC for any "system side write" into sram buffer. Reading an
uninitialized memory results in ECC Error from sram wrapper.

Hence we must initialize/prefill SRAM buffer by any data before writing
anything in SRAM from system side. To initialize SRAM user can use "READID"
NAND command with read bytes equal to SRAM size. It will be a one time
activity post boot

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
[scottwood@freescale.com: fix fsl_ifc_sram_init prototype]
Signed-off-by: Scott Wood <scottwood@freescale.com>