ARM: OMAP2+: gpmc: enable BCH_HW ecc-scheme for AM43xx platforms

Fixes: commit 0611c419
ARM: OMAP2+: gpmc: update gpmc_hwecc_bch_capable() for new platforms and ECC schemes

Though the commit log of above commit mentions AM43xx platforms, but code change
missed AM43xx. This patch adds AM43xx to list of those SoC which have built-in
ELM hardware engine, so that BCH ecc-schemes with hardware error-correction can
be enabled on AM43xx devices.

Reported-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Pekon Gupta <pekon@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>