mtd: rawnand: qcom: cleanup qcom_nandc driver

Perform a global cleanup of the Qualcomm NAND
controller driver with the following improvements:

- Remove register value indirection API

- Remove set_reg() API

- Convert read_loc_first & read_loc_last macro to functions

- Rename multiple variables

Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>