Support hardware based BCH error correction

configname: CONFIG_MTD_NAND_OMAP_BCH

Linux Kernel Configuration
└─>Device Drivers
└─>Memory Technology Device (MTD) support
└─>Raw/Parallel NAND Device Support
└─>Support hardware based BCH error correction
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This config enables the ELM hardware engine, which can be used to
locate and correct errors when using BCH ECC scheme. This offloads
the cpu from doing ECC error searching and correction. However some
legacy OMAP families like OMAP2xxx, OMAP3xxx do not have ELM engine
so this is optional for them.