mtd: spi-nor: cadence-quadspi: Refactor indirect read/write sequence.

Move configuring of indirect read/write start address to
cqspi_indirect_*_execute() function and rename cqspi_indirect_*_setup()
function. This will help to reuse cqspi_indirect_*_setup() function for
supporting direct access mode.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>