mtd: nand: qcom: fix config error for BCH

The configuration for BCH is not correct in the current driver.
The ECC_CFG_ECC_DISABLE bit defines whether to enable or disable the
BCH ECC in which

	0x1 : BCH_DISABLED
	0x0 : BCH_ENABLED

But currently host->bch_enabled is being assigned to BCH_DISABLED.

Fixes: c76b78d8 ("mtd: nand: Qualcomm NAND controller driver")
Cc: stable@vger.kernel.org
Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
Reviewed-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>