mtd: rawnand: qcom: Pass 18 bit offset from NANDc base to BAM base

The BAM command descriptor provides only 18 bits to specify the BAM
register offset. Additionally, in the BAM command descriptor, the BAM
register offset is supposed to be specified as "(NANDc base - BAM base)
+ reg_off". Since, the BAM controller expecting the value in the form of
"NANDc base - BAM base", so that added a new field 'bam_offset' in the NAND
properties structure and use it while preparing the command descriptor.

Previously, the driver was specifying the NANDc base address in the BAM
command descriptor.

Cc: stable@vger.kernel.org
Fixes: 8d6b6d7e ("mtd: nand: qcom: support for command descriptor formation")
Tested-by: Lakshmi Sowjanya D <quic_laksd@quicinc.com>
Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
Acked-by: Mark Brown <broonie@kernel.org>
Tested-by: Gabor Juhos <j4g8y7@gmail.com> # on IPQ9574
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>