mtd: rawnand: brcmnand: Add BCMBCA read data bus interface

The BCMBCA broadband SoC integrates the NAND controller differently than
STB, iProc and other SoCs.  It has different endianness for NAND cache
data.

Add a SoC read data bus shim for BCMBCA to meet the specific SoC need
and performance improvement using the optimized memcpy function on NAND
cache memory.

Signed-off-by: William Zhang <william.zhang@broadcom.com>
Reviewed-by: David Regan <dregan@broadcom.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20240223034758.13753-12-william.zhang@broadcom.com